I'm sure the same applies worldwide. But Britain is an island, so we have a greater propensity to travel than most, so more airlines are formed. We are also a fairly open economy, so start-ups are easier here than in some other jurisdictions.
What I think the number of failures shows is that aviation is a precarious business, that so many factors can affect - think terrorism, fuel prices, recession, regime change, weather, etc etc.
Oh, just thought of another one - Paramount.
And Air Exel.
Alidair
Air Bridge Carriers
Air Ferry
Invicta International
Capital
Euro Direct