Most of the Scottish border is fairly physically obvious, unlike Wales (although the Severn bridge is).
Tens of thousands of people live on islands other than Britain and Ireland. Much of Scotland is not even considered UK mainland by delivery firms, even major places such as Perth.
Really? Perth? You can go on uninterrupted 70mph roads from London to Perth.
What? Perth isn't considered part of the mainland? How is that possible? My family is from Perthshire (Blairgowrie) and I've visited a bunch. It's definitely part of the island!!!
I can understand Lewis and Harris or the Shetlands (they're separate islands without bridge links), but Perth doesn't make much sense. And I would have assumed Skye was considered "mainland" as well, at least now that there's a bridge.