That makes sense. It was a real question I had, I have no opinion of the matter.
I guess the UK sees itself as having a more stable economy that other European Union countries, so it would benefit from having a separate currency (but the other countries would be hurt by not having a very strong country adopt the euro).
Not more stable, but historically out of phase. i.e. when Germany has done well the UK has had a down phase and vice versa.
The killer flaw in the Eurozone is not appreciating how useful different currencies are for dampening the effect of such differences. Greece is the classic example, where for them the Euro was too strong making them globally uncompetitive, leading to a nasty downward spiral, whereas Germany benefit from their exports being far more competitive than they would be if they were still using the DM.
I guess the UK sees itself as having a more stable economy that other European Union countries, so it would benefit from having a separate currency (but the other countries would be hurt by not having a very strong country adopt the euro).