There was a case where a thief used a stolen card to pay for a long-odds bet in a High Street bookmaker's shop. When he tried to collect the (not insubstantial) winnings the cashier told him that it had to be paid to the account related to the card. He protested vociferously and it was at that point that it was noticed that the card bore a woman's name and the police were called.
However the betting firm decided that the bet was still valid and therefore paid the winnings (amounting to several thousand pounds) into the woman's account anyway.
If the card owner in the National Lottery case can be identified, it will be interesting to see whether Camelot decides to
(a) refuse to refund anything ; or
(b) only refund the £10 ticket purchase price ; or
(c) pay the £4m into the card owner's account.