After the 'Great Recession' it's hardly unexpected, and at least there is 'shoots' of a recovery; unlike throughout large swathes of Europe.
If someone has a bad accident, and is in a wheelchair, it takes time to learn how to walk again.
Don't vote tactically, vote for what you believe in. If you believe in UKIP vote for them.
Also Crawley is hardly a 'Labour stronghold' the MP's a Tory!