[logfromblammo]

So... Pitbull Studio (Epic UK) for something using Unreal Engine 4?

We don't have an international union, so I don't exactly have any leverage here, but I want you to be paid more. Do you seriously think that you are so far below the median level of skill for a C++ programmer with a degree and two years of experience, that you should be paid so little?

Go. Look for another job, and find out just what they would be willing to pay you. With an offer in hand that you could accept on its own merits, go to your current employer and, without mentioning anything about your other offer, ask that your pay rate be reevaluated, to match your skills in the current market. If you don't get a significant payrise, then at that point, you can decide whether it is worth more to have extra cash in your hand, or to keep a job that you know you like, but pays peanuts--stale peanuts at that. Remember, you don't have to accept any offer you don't like.

For now, you seem to have decided that you like your current job £15-20k/year more than anything else you think you could possibly get.