Queenie by Jacqueline Wilson
Ex-library book, kindly donated. Worn on the cover, stickered up on the spine, but otherwise perfectly readable
 
It's 1953, the year Elizabeth is to be crowned Queen of England.

Elsie Kettle can't wait to go to London to see the celebrations on Coronation Day. Elsie lives with her Nan - her mum works as a showgirl, so she's not around very often. Spirited and imaginative, but often lonely, Elsie longs for a best friend. Luckily, she and Nan are very close; Elsie just wishes she was allowed a cat to keep her company sometimes.

Then tragedy strikes.

Nan and Elsie both fall ill with tuberculosis, and Elsie finds herself whisked away to the children's ward of the hospital. Confined to bed for months on end, Elsie finds it very hard to adapt to the hospital's strict regime. But she invents astonishing ways of entertaining the other children on the ward, and for the first time finds herself surrounded by true friends - including Queenie, the hospital's majestic white cat.