Best way to give to grandchildren?

I don't know the most profitable way, but I bought Premium Bonds for my 6 GCs. They love it when they receive a cheque in the post, which is quite frequently, although usually only £25. They either share with their siblings, spend it on something special or put it into their savings account.
I bought a similar number of PBs for myself, but can only remember one win in 15 years!

Junior isa. Can be converted to normal isa later on and no tax to pay.

Jingle, thanks, I didn't know about junior isa's. Does the cash become available to the child at age 18, and if it's in the child's name - who, if anyone, could access the isa before that age?
Sorry if I'm asking you to be our isa expert for grandchildren, I'll accept it if you tell me to find out for myself

Iam64 Try this link for explanations and advice:
www.moneysavingexpert.com/savings/junior-isa

thanks Flick