In reply to Pete Pozman:
Yeah, nightmare. I have been so close once or twice, and recently had to contest a fraudulent online card purchase for £1200!! How they got the card details I have abs no idea. Fortunately the retailer and the credit card company were very helpful (if initially suspicious) and got it sorted. The perpetrator got greedy and had another go, which they caught and stopped.
If you need multiple currencies, Wise are very good, and you can hold GBP balances in an interest account.