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thanks for your answers,
I actually live in australia and was going to build a house on it for him to live in. He signed the papers for the house to be built and i again was going to pay for it, the work on the house has begun and we recently received an invoice in his name from the builder.
As for him saying it was a gift, i also have 3 other children and niether of these have received any gifts, as it was a fair amount of money, i would not have enough for any of the others to have the same. and if it was a gift would it be classed as a capital gain in the uk. I thought you can give your children money but over a certain period of time. ie 7 years, otherwise this would be classed as an inheritance tax.
thanks again