Horse chestnut tree.

You can make a sort of fuel from it.
But don't.
In the WW2, a method of making a chemical to assist the production of cordite (The explosive used in BIG guns) was invented using conkers.
So, let that idea pass :-)

Oh dear!. thanks for that information,I won't be trying that then. much appreciated though.

you could roast them for eating.

NO NO NO!
Do not eat them!
HORSE chestnuts are poison, SWEET Chestnuts are edible.
Different tree.

A toxic substance called aesculin is in the Horsey. To make it safe you would need to boil the things about 6 times, each time with fresh water. To get what? A yellow tasteless mulch that a dog would prefer to roll in than eat.

oops , ive just googled chestnuts and bbc recipe for them... i never knew there was a difference, think the recipe pages on bbc web page should maybe point that out, thanks for letting me know they are poisonous

I think pigs can eat them, but don't quote me!

O.K.! I think I'll just leave them alone,many thanks to you all.