Answer: Lord Byron

The poet Lord Byron was awarded the first blue plaque in 1867. His house was demolished in 1889 and the site is occupied today by a John Lewis department store.

There is no clear evidence though to show which house in Holles Street Byron lived in, so it's possible that none of his plaques, past and present, has actually marked the correct spot. 

Answer: Napoleon III

The plaque to Napoleon III, the last French emperor, was installed in 1867. The design includes the French imperial eagle.

It is said that he left his London home in King Street in a great hurry to return to France when he heard of the overthrow of King Louis Philippe in 1848. His bed was left unmade and the bath was full of water.

Answer: Red

Michael Faraday's plaque - put up by the Society of Arts in 1876 - is the oldest in Marylebone, and marks the house in Blandford Street where he was apprenticed to a bookbinder.

Answer: Oskar Kokoschka

A plaque to the Austrian painter Oskar Kokoschka, who died in 1980, was erected at Eyre Court on Finchley Road in St John's Wood.

Since then, English Heritage has put up over 360 plaques, bringing the total across London to more than 900.

Answer: Rectangular

Non-circular plaques have sometimes been made to better fit spaces on buildings.

Other rectangular plaques include those to Clive of India and the novelist Wilkie Collins.

Answer: Ida Mann

The site of Mann's blue plaque - 13 Minster Road in West Hampstead - was her home from 1902-34.

She was the first woman to hold the title of professor at Oxford University and played a key role in the development of contact lenses.

Answer: Herbert Chapman

Chapman, who is commemorated by a plaque that was installed at his home in Hendon in 2005, is considered to be Arsenal's greatest ever manager.

With Chapman as manager in the 1920s and 1930s, the team won the FA Cup and twice won the Football League First Division.

Chapman also had a major impact on how the game is run, helping to introduce floodlights and numbers on players' shirt

Answer: 20 years

In order for someone to be nominated for a blue plaque, at least 20 years must have passed since their death.

In addition, the building associated with the figure must survive in a form that the commemorated person would have recognised, and be visible from a public highway.

Answer: 19

There are currently 19 examples of London homes with double commemorations.

These include 20 Maresfield Gardens (Sigmund Freud and Anna Freud), 29 Fitzroy Square (George Bernard Shaw and Virginia Woolf), 48 Paultons Square (Samuel Beckett and Patrick Blackett) and 4 Carlton Gardens (Lord Palmerston and Charles de Gaulle).

Answer: Bronze

Bronze was the favoured material for the plaques put up by the London County Council in the years just before the First World War.

These plaques are elegant but do not call out to passers-by in the way that blue ceramic roundels do.