1994 Alderney D-Day Anniversary £25 Gold Coin

Despite their name, "Westminster Mint" isn't actually a mint, it's a mass-marketing coin corporation. Their "products" are not generally looked upon with favour by coin collectors, since coin collectors are not the primary target market for Westminster. They sponsor the production of "coins" like these from various private mints (I think "Tower Mint" is Westminster's main source mint).

Coin catalogues are often slow at cataloguing coins from private mint ventures such as this, because publicity surrounding their launch does not last very long on Westminster's website - once the coin sells out, Westminster loses all interest in them - so things like actual mintage figures are hard to verify, and it can also be difficult obtaining verification from their flag-of-convenience countries that the coins are in fact legal tender.

In the case of these specific coins, there are two verified legal tender gold coins of that date and denomination listed in the Krause catalogues and on the NGC database; this one and this one. They have different catalogue numbers so they have different designs, but since there's no picture of either, I'm afraid I can't tell you which if any of these listings refers to your coin, but from a value point of view, it doesn't seem to matter; they're both listed as "bullion value only" (which is currently at US$415).