I understand you want a briotish made hull bit have you considered the SAfrican built FALCON 700RSR Racing LOA 7mtrs?
The boat has 150 VMax HPDI Yam on it and and it does speeds near and over 60 knots depending on sea conditions. The construction is light but very strong due to a special way FALCON manufactures this boat. It comes with guarantees that I am sure will be honoured by their rep in France.
The boat has wan all the RIB races in SAfrica for the last 3 years I think in F3 and F2 category. This is something considering the type of seas and racin g conditions they have there. I know I've been on it and is ausome.
Have a look at the attached photos and if you like any further info drop me a line