Not a lot of people will be able to comment openly.
I can only say that through 2005 every UK outfit doing FAA training has found it very hard to get FAA examiners (be they FAA employees or the much more usual DPEs) to come over to the UK.
They still do come over but more to other European countries, and they go straight to the pilot, not via some training firm.
They used to be able to just pop over anytime, make $800-$1000 per checkride, plus all travel+hotel expenses recovered, but now they have to register with the FAA in the USA, and the red tape has put most of them off. Some people have not seen an examiner here since early in the year.
To what extent the CAA is responsible for this I have no idea but obviously it suits them completely.
The need for the DfT permission just makes matters worse. One cannot find a DPE who will do it for nothing, of course, so there is no way around this if flying in UK airspace. And nobody except owners, or Directors of ltd companies with 4 or less Directors, will ever get the DfT permission (details on the DfT website).
This has drastically cut back the customer base, because while UK based FAA training is still easy to arrange, without a clear UK-based checkride option at the end there is little point in flying here. One may as well do the written here, meet all the FAA logbook requirements (which can be done in a G-reg with a JAA instructor) and then sod off to USA and spend a week or two out there flying and learning the US-specific obscurities which the examiner will so delightfully quiz you on in the oral.
People just have to go off to Florida - just like they have been doing for years. Nobody gains.