Like my wardrobe, which is full of clothes I've had for years and haven't worn, my bookshelves are full of books I've had for years and never opened.
However, there are several that I use all the time.
'Walking Jane Austen's London' by Louise Allen is invaluable when I'm writing a Regency set in London. I also have her 'The Georgian Seaside' which I shall use when I write next summer's book for the Regency romantic box set. This box that will be books set at the seaside.
I also use the 'A-Z of Regency London' and the 'A-Z of Victorian London' as well as the facsimile copy of an original A-Z of 1940s London.
My go to books for World War II are 'Wartime Britain' by Juliet Gardner and 'How We Lived Then' by Norman Longmate. I've also found 'Christmas on the Home Front' by Mike Brown essential with several of my World War II sagas.
Of course I have every autobiography written by female ATA pilots as well as a dozen or more books about the RAF and several biographies by Spitfire pilots.
I also find it useful to read good fiction, especially the three books by Derek Robinson about the RAF.
I'd be interested to know what research books you would never take off on your shelves.
Fenella J Miller