When our parents and grandparents, great grandparents, etc., were keeping the home fires burning during WW2, no one here starved. No one here had any reason to have a poor diet. There were huge efforts made to make the most of what we had, to manage to keep the entire nation healthy.
That wasn't the case elsewhere.
We were very fortunate as well as very organised, and though the UK was bombed, it's farmland was never obliterated the way fields abroad were.
Every scrap of uneaten food was saved and boiled up and fed to the pigs....so there was still bacon. Limited but there was bacon, and butcher meat, and eggs, and everyone had a right to a share.
Horses were both the engines of the farms and the transport and the steeds of the military and not seen as food.
It's a cultural difference that was reinforced by the lack of dire necessity. We never needed to boil up leather to make it palatable, we never needed to roast tree inner bark to eke out flour, nor grind up eggshells to make sure our children had enough calcium.
It's not just WW1 or 2 though, it goes back for centuries. Napoleonic wars, and so on.
The British Isles have not been successfully invaded in a very long time. I know the British Channel islands were not so lucky, and they endured the hardships of occupation; I'm not belittling that.
The Romans thought horse and dog meat to be profane, and it was only offered to the gods of the underworld.
I think it was Pope Gregory who banned the eating of horses in the 700's, though a pagan rite survived in Germany, and then the French really took to eating the horses after their revolution, because horses were of the nobility
So, basically Brits just never did eat horses, or dogs, not since Britain became recognisably Britain.