Thanks to all posters. I am now planning to rumble up to my man in Grimsby, JW at Tommy Sant who pretty much rebuilt the car a few years ago.
In answer to those posters asking how to recognise a cat issue I can only recount my experience - the exhaust note began to resemble a sickly tractor and soon after that a warning light came on which my local garage here in Suffolk confirmed was 'engine management' and also that both cats and sensors were "shot". They enquired of Rutters for replacement parts but their parts dept seem to have adopted continental holiday habits (no reply as yet). A pity as I've had the tonneau on permanently since April enjoying this fine English summer... .
