Comment by pjc50

Everyone else telling you about civil forfeiture; I'm going to mention the original James Bond novel Goldfinger, in which part of the early plot is exactly Auric Goldfinger hiding gold in the panels of his Rolls-Royce in order to smuggle it out of the UK, which was illegal at the time. Even for gold legitimately owned.

(historical background: https://www.chards.co.uk/guides/exchange-control-act/785 )