> 37.7 GBP per kilo for 12K carbon fiber is expensive though..
> In China, Toray T700 12k 50c costs about 27 GBP per kilo.

What amounts?
Directly from Toray? How many middlemen/businesses are involved?

What's the sales tax rate in China? How high are all the other taxes?
What are the costs for employees? This involves work hours per year, paid vacation, health and accident insurances, retirement, unproductive paid time, sick leave (= temporary or longer lasting), inability to fire employees when there's not much business, and so on.
What are costs for facilities? Rent, energy, taxes, interest rates...

All that differs from country to country. There's are many reasons lots of stuff is currently produced in China, because the average worker in Europe costs an employer roughly 10 times as much as the average Chinese worker.

So who ultimately pays all that money? The business? NO, of course not, the customer has to pay all these expenses.