The UK Government set up the Child Trust Fund in 2005 to allow parents to start to invest for their child's future with the gift of a £250 voucher but after a year, some 30% of households had failed to redeem this voucher so the HMRC automatically set up savings accounts for these children. On their seventh birthday the Government contributed a further £250 or £500 for low income families. This money has been quietly accumulating interest and once the child reaches 18 years old it can then be claimed. Expect these accounts to be worth £1,000 or more.
If you have set one up but can't remember with who or your Child wants to locate his money then try using this service from The Share Foundation(its run by a non profit making charity who will not charge for locating the money). It will tell you how much money there is and where it is held.Your 18 year old Son or Daughter will need to provide an e-mail address and National Insurance number and make sure they sign the form-
find cft.sharefound.org
or there is a Government web site search at
www.gov.uk/child-trust-funds/find-a-child-trust-fund
It's worth pursuing.Good Luck in your search
Kind Regards