[panarky]

Fees for international money transfer across currencies are always opaque and borderline deceptive.

If this is truly fixed cost, it would definitely be the first, but it's right to be skeptical.

The only reliable way to discover the actual cost is to do a round trip.

Convert a million X to Y, then convert whatever Y you get back to X, and the difference between that and the original million, divided by two, is the real cost.

Naturally this website won't show you that, because you can only convert from pounds but not back to pounds.