There is an interesting debate raging in another place regarding the efficacy or otherwise of industrial action, particularly in the UK. Some people seem to believe it is merely a case of willpower. If we had the guts to take more industrial action - specifically in the UK - then we would see better results.
I find this unpersuasive personally. If I was a shareholder in any large company, the sort of wholesale shift in industrial landscape which would be caused by a capitulation to strike action, threatened or otherwise, would be detrimental to my long term interests. It would undermine every pay negotiation going forwards and potentially result in far greater disruption in the future (witness the railways). This, I personally believe, is why it is unlikely that industrial action would cause a meaningful closure in the pay disparity.
People have correctly identified that what has caused the upward pressure on pay in the US is recruitment & retention. These issues are not playing big in the UK as of yet, the chief reason being unlimited access to lour hour cadets.
The other thing to consider in all of this is the wider economic differences between the UK and the US. The tax regime, economic growth etc. All industries and professions in the UK especially have seen real terms stagnation or decline in their purchasing power over the last 20 years, particularly since the financial crisis. We are hardly alone in this respect.