Well the fact that drugs are twice as expensive (or more) in the US* and the fact that the US accounts for a huge chunk of government funding into the relevant sciences are part of the reason why drugs are so cheap overseas. British taxpayers buying drugs in Britain are effectively getting a subsidy from US taxpayers even though they don't pay into the pot, so this all seems like a stroke of cosmic justice where I'm standing. Of course, I doubt the British tax authorities care much about what I think.

* Why? Remember how bargaining works: the biggest customer gets the best deal. First imagine Kaiser, Wellpoint, and Aetna sitting down at the bargaining table. Now imagine Canada sitting down at the table. Now imagine the European Union sitting down at the table. But at least our insurance companies are more efficient due to competition, right? Spoiler: not even close, and that's before you take into account the costs they offload onto the rest of the system in the form of incompatible claims policies, paperwork, and exploitation of information asymmetry against consumers.