I can kind of see why this would be the case, actually - I think it's the massively inflated headline prices that they are putting on their prizes which means that they're limited to a few areas with really high prices in general. If it were, say, £2 milion, they'd be able to find loads of houses all over the UK that would be viable prizes people could actually move into or use as a holiday home, but if they want to claim it's worth £5 million (which I don't for a minute believe this one is) the available properties are likely to be a bit more niche, or too big or otherwise complicated. They struggle in Scotland for that reason - most of the Omaze-suitable houses are probably worth less than £2 million. In the county I live in, there's literally nothing on the market for over about £2.5 million, and that's an actual castle.