One thing that indicates it is a scam would be the exorbitantly high salary that is not in proportion for the kind of job that you are supposed to do.
Such fictionally high salaries are simply there to trick you in and to make him send your "application". Once you have done, you will be asked to pay for a pretend visa or something else, but in the end you have no job, no visa, have lost your money and can't get it back.
The other thing is the crap story you are told by the scammer: If you are hired for a job in the UK, you should consider this: If the job offer were genuine, why should someone need to employ someone from overseas? The UK is currently hit by a crisis in its national economy and a high unemployment rate due to the worldwide bank disaster caused by irresponsible Wall Street speculants and other banking yuppies that exist to destroy national economies that produce real value!
Just use your brain and a bit of common sense and don't believe everything these idiots are telling you.
In the end, you might be the idiot and the victim and might lose money on some crooks like that.
These messages exist to protect unsuspecting people like you!