Qinetiq, the "british" defence research agency, is mainly structured around American interests (Carlyle Group) since the privatisation. Fact.
So those people sold their "formerly" independant research capabilites (Boscombe Down, Farnborough) to the yankee dollar, as rightly said by glad rad
Yes, in the Rafale everything is French (engine, radar, ECM, nuclear missile) - to the great displeasure of US.
Pity our current government is currently sold to US interests (the result: a pityful 18% approval rate in the population) So things might change soon - wait for next elections ...
Back to the sub'launched missiles : Trident is american, so if they are removed, the Royal Navy can revert to combat divers on kayaks to deliver those "proudly british " warheads