Many of the books I read as a girl were set in London. One of the earliest, a children’s book of verse by A.A. Milne called ‘When We Were Very Young‘, had ‘Buckingham Palace’, which begins:

They’re changing guard at Buckingham Palace –
Christopher Robin went down with Alice.
Alice is marrying one of the guard.
“A soldier’s life is terrible hard,”
Says Alice.

Milne published this in 1924, when George V was King. The video below has changed ‘King’ to ‘Queen’.