I'm an outsider looking in, so i hope you won't mind an answer from one of your neighbours!
Britain can be beautiful, but the sprawl of cities has blighted this - soon London, Manchester, Brimingham and Liverpool will be distinguishable only by post code.
The rise of yob culture is all that your media shows the outside world - if it's that prevalent you have a huge problem to overcome.
The taxes you guys pay are ridiculous - income tax, fuel tax, council tax etc etc - how many times do you need to be taxed on each pound?
One commentator has cited the EU - yet I would hazard a guess that the majority of those emigrating are to Ireland, France and Spain, followed only then by non-EU countries like the US and Oz.
There may be plenty of jobs, but as Weeal states, you'd need two of them to survive on the whole.
A vocal minority get their political views from the Mail or the Sun, and a percentage of them never actually think about this.
I'm sure immigration has played a role, but the policies of many decades have allowed ghettoisation of areas of your cities.
And to be honest, if you read any thread in the law section, there are loads of reasons to move away - there seems to be a serious issue regarding community and neighbours.
Lastly from me - I've said it many times on here, you guys are terrified to assert yourselves as English (not so much the Scots and Welsh) for fear of upsetting someone - what's that about?
Just some thoughts.