23 things you (probably) didn't know about No 10 Downing Street, the official residence of Britain's prime ministers

No 10 Downing Street was initially No 5

The king’s gift was, in fact, two houses: one fronting onto Downing Street and a larger one overlooking Horse Guards behind. Walpole moved in only once the two had been combined and refurbished, becoming the first premier to call Downing Street home in September 1735. The house was then actually No 5, and remained so until 1779 when it was renumbered.

Its historic colour is the result of air pollution

No 10 Downing Street’s distinctive brickwork is not actually black – restoration works in the 1960s revealed that the terrace was built with yellow bricks, subsequently blackened by two centuries of inner-city air pollution. A black colourwash is used today to maintain its historic appearance.

A brewery once stood the land

The land on which Downing Street stands was once part of the ancient Roman, Anglo-Saxon and Norman settlements of Thorney Island. Later home to a brewery, it was in the hands of the Crown by the reign of Henry VIII, sitting on the edge of the king’s vast Whitehall Palace site.

A house there was leased by Elizabeth I to one of her favourites, Sir Thomas Knyvet, in 1581, and it was his niece, Mrs Hampden, who was residing in it when the land was confiscated under Oliver Cromwell (although she still continued to live there).

The house was built by one of Oliver Cromwell's spymasters

A “perfidious rogue” and “ungrateful villain” was how diarist Samuel Pepys described the man who gave his name to Britain’s most famous street. Sir George Downing was a former preacher who became one of Cromwell’s most high-profile spymasters in the wake of Charles I’s execution in 1649, only to switch sides when the Restoration loomed.

Having traded his secrets for a pardon from the exiled Charles II, Downing went on to round up his former comrades for execution, receiving a baronetcy from his grateful king and settling into a new life as a government administrator – admired for his capabilities, but despised for his self-interest.

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The former Crown land in Whitehall, Downing had acquired in 1654. Undeterred when the transfer was declared null and void at the Restoration in 1660, Downing brazenly told the king that it had come to him in payment of a debt, and was granted a lease of the site and liberty to build on it. With an eye solely to profit, he erected a series of 15 to 20 terraced houses and gave the street his name.

It wasn't built to last

Sited on boggy ground and cheaply constructed with shallow, ineffective foundations, Sir George Downing’s terrace was not built to last. An £11,000 ‘Great Repair’ begun in the 1780s was the first of a series of works that failed to fix the issues.

Having suffered a battering in the Blitz, No 10 was in a desperate state by the 1950s: riddled with dry rot, the risk of fire was so great a firefighter was employed full-time, and there were concerns that the uneven floors might give way. Demolition was, however, rejected as an “act of impiety” and in 1960, Prime Minister Harold Macmillan moved out while the foundations were strengthened and the building renewed – a project that took three years and cost over £1 million.

One prime minister used it to try and convince prostitutes to change their ways

William Ewart Gladstone had one of the most eccentric hobbies of all the prime ministers who have ever resided in Downing Street: late in the evening he would walk to Soho, pick up one or two ladies of the night and take them back to No. 10, where he would attempt to convince them of the error of their ways.

The iconic black door was briefly painted green

The most famous front door in the world has not always been black: in 1908 it was painted green on the instructions of Prime Minister Herbert Asquith, only to go back to black at the end of his tenure in 1916. Originally made of oak, the door was replaced with a heavy-duty steel version for security reasons in the 1990s.

A 'lady in pink' may haunt the house

Only one prime minister in history has ever reported a ghostly presence at No 10 Downing Street: Harold Wilson and his cleaner both claimed they had – separately – seen a lady dressed in pink in the private apartment.

Alms have been given from its door

Some of Downing Street’s most famous visitors have been greeted and photographed on its doorstep, but during the 18th-century premiership of Lord North you were more likely to find a group of poor people huddled there, as every Sunday he handed out money and food.

Protestors used to be able to march up to the front door

In the centuries before the famous gates to Downing Street arrived in 1989, protesters could – and did – march right up to the prime minister’s front door: most notably the suffragettes.

• Read more | Emily Davison: the suffragette martyr

During the so-called ‘battle of Downing Street’ on 22 November 1910, a total of 159 people (including three men) were arrested while taking part in protests against Herbert Asquith. The suffragettes would return to Downing Street time and again during the course of their campaign, breaking windows, chaining themselves to railings and directly confronting politicians.

The IRA attacked No 10 in 1991

The Irish militants targeted No 10 on 7 February 1991. Prevented from getting into Downing Street itself by the gates installed less than two years previously, they fired their three mortar bombs from a transit van parked out on Whitehall.

There were no mod-cons for incoming prime ministers

When Labour’s Ramsay MacDonald came to power in January 1924, he and daughter Ishbel were shocked to find that the state provided so little furniture for the large and rambling house at Downing Street, and none of the cutlery, crockery or silver necessary for official entertaining – not even any bedsheets.

Unlike most of his predecessors, MacDonald had no luxury country home on which to call, and the provisions of his modest house were nowhere near sufficient. Ishbel was sent to the January sales to stock up, and would later recall having to help her father by funding more items from a small personal inheritance.

Nor were there any servants

Engaging (and paying for) Downing Street’s domestic staff has always been the responsibility of the tenant. During David Lloyd George’s tenure the staff were all Welsh nationals, who spoke to each other – and often the prime minister’s family – in Welsh.

By the mid-19th century it was surrounded by brothels and gin parlours

Minutes from the Houses of Parliament, we can think of no better location for the prime minister’s residence than Downing Street. It was not so in the early 1800s. By then, it was “a dingy solitary street with a dirty public house on the corner and a row of third-rate lodging houses between it and the Foreign Office” – a building which was itself dilapidated.

The surrounding area was becoming seedier every year, too – by 1846 there were 170 brothels and 145 gin parlours within the vicinity. Plans to demolish the entire north-side terrace were seriously considered, but numbers 10, 11 and 12 survived.

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Not every prime minister has called it home

It has never been a requirement for the prime minister to live at Downing Street. Many Georgian and Victorian premiers – including Lord Melbourne, Sir Robert Peel and Viscount Palmerston – preferred to remain in their own London townhouses, using No 10 as an office, or allowing their chancellors to move in. Of the 31 men in office between 1735 and 1902, only 16 resided there. Some more recent prime ministers have elected to live in the spacious flat at No 11.

One operation has been performed in the house

The only operation known to have been carried out at No 10 is the removal of a facial cyst troubling William Pitt the Younger in 1786. He reportedly rebuked the surgeon for taking half-a-minute longer to perform the procedure than his estimate of six minutes.

Royal visits are not unheard of

Although the monarch has not attended cabinet meetings regularly since the reign of George III, the royals have been frequent visitors to No 10. Queen Caroline came for breakfast a week after Sir Robert Walpole moved in; Edward VIII was smuggled in for secret talks with Stanley Baldwin about his proposed marriage to Wallis Simpson; and George VI risked the air raids to dine with Winston Churchill during the Second World War.

'Mousers' are among No 10's most important residents

Mice have long stalked the corridors of No 10, meaning that government officials have often relied on ‘mousers’ for help. Larry is just the latest in a long line of feline residents, including Winston Churchill’s so-called ‘Munich Mouser’. Churchill’s nickname for the cat reflected the fact that the moggie’s previous owner, Neville Chamberlain, had signed the controversial Munich Agreement in support of German appeasement.

• What was written on Neville Chamberlain’s piece of paper?

The first Downing Street Christmas tree was introduced by Thatcher

Downing Street’s Christmas tree is one of its more recent traditions, begun by Margaret Thatcher. Since 1999, it has been supplied by the winner of a competition organised by the British Christmas Tree Growers Association.

It was a wartime hub in WWI, but not WWII

During the First World War, No 10 was a hive of activity. In January 1917, David Lloyd George set up a group of wooden huts on the lawn (known as the ‘garden suburb’) in order to house extra staff.

It was much quieter in the Second World War. Amid concerns about the house’s stability, Winston Churchill was persuaded to move into a flat above the underground bunker we now know as the Churchill War Rooms. He did, however, insist on using No. 10 regularly for meetings and dinners, so certain rooms were reinforced with steel and a shelter was constructed under the house, where the prime minister was once forced to seek refuge with George VI.

There are 61 years separating the oldest and youngest incumbents

Taking office aged 24 in 1783, William Pitt the Younger is Britain’s most youthful premier to date – but also the youngest to live at No 10, moving in as chancellor aged 23. William Ewart Gladstone was the oldest incumbent, leaving Downing Street at the age of 84.

It is unclear why the zero in 'No 10' is askance

Theories abound as to why the zero on No 10’s front door is slightly askew. Some believe the original number was badly fixed and the position has been forever preserved in tribute; others that its angle was deliberate, replicating the tilted letter ‘O’ in an ancient Roman style of lettering that had been adopted as a typeface by the Ministry of Works.

Felicity Day is a freelance writer specialising in the history of the Georgian and Regency eras