I'm not absolutely sure, and I've put them in date order because order of preference is too hard, but I think these might be the ones I'd keep from my collection of nigh on two thousand, if I could have only twenty five. It would be a devilish hard choice, mind!
Alice Through the Looking Glass Lewis Carroll (1864)
(or Thogh the Looking Glass, as I was convinced it was called on first reading, aged seven)
Eight Cousins (or possibly An Old-Fashioned Girl) Louisa M Alcott (1875)
(Both much nicer than Little Women, in my not so humble opinion)
Martin Pippin in the Apple Orchard Eleanor Farjeon (1921)
Bunkle Butts In M Pardoe (1943)
The Little White Horse Elizabeth Goudge (1946)
(still the favourite!)
The Lost Staircase Elinor M Brent-Dyer (1946)
(Brent-Dyer in a more romantic/ historic mood)
Eudoria’s Broomstick Victor Knowland (1950)
(totally obscure fantasy adventure, but with typically postwar emphasis on food - especially steamed puddings, for some reason)
A Swarm in May William Mayne (1955)
The Warden’s Niece Gillian Avery (1963)
(I had the opportunity of telling the author how much I loved it and she was disappointed because it was one she'd written so long ago!)
Nurse Matilda Christianna Brand (1964)
(always makes me think of my hordes of cousins, knowing the author was similarly placed)
Bottersnikes and Gumbles A S Wakefield (1967)
(more fantasy - the cranky snikes versus the jolly gumbles in the Australian Bush)
The Owl Service Alan Garner (1967)
(still one of the most haunting things I've ever read)
A Wizard of Earthsea Ursula K Le Guin (1968)
Creed Country Jenny Overton (1969)
(family dynamics and historical research, so two favourite themes combined)
Septimus and the Danedyke Mystery Stephen Chance (1971)
(about as much a children's book as Garner's are...)
The Cuckoo Tree Joan Aiken (1971)
The Cricket Term Antonia Forest (1974)
Robinsheugh Eileen Dunlop (1975)
(more time travel, this time in Scotland)
The Bassumtyte Treasure Jane Curry (1978)
(the one I always read when I'm ill, for some reason: it always takes me out of myself, perhaps because of the time travel/ reincarnation element)
A Midsummer Night’s Death K M Peyton (1978)
Fire and Hemlock Diana Wynne Jones (1984)
(technically by far the best of her books - this one's literature, to my mind)
The Hounds of the Morrigan Pat O’Shea (1985)
They Do Things Differently There Jan Mark (1994)
(completely surreal!)
Artemis Fowl and the Eternity Code Eoin Colfer (2003)
The New Policeman Kate Thompson (2007)
Celtic fantasy with lots of Irish traditional tunes woven in
What I noticed when I first attempted this exercise was the preponderance of 1960s and 70s titles - so books I'd encountered in my teens and twenties rather than my childhood. Sadly, I notice that I’ve virtually given up on contemporary children’s books, apart from those by authors whose work I already know (always happy to read Diana Wynne Jones, Eoin Colfer, Kate Thompson), which is a great shame. But too many of the current crop are all alike to me – too often I find that fifteen or twenty pages in I’m struggling to remember the characters’ names – and can’t feel very bothered about them anyway. That's a fairly unfortunate observation when you consider that one of my favourite genres is fantasy, which should be memorable if nothing else.
Publishers are far too obviously desperate to find the next J K Rowling. There actually may not be one, guys, or at least not for a bit. I’d say the previous comparable equivalent was Enid Blyton, and she published her last full length work in 1965!