Firstly, to answer Biggles, regrettably that is the case. The CAA cottoned on to the fact that persons failing their CVD tests were going overseas to other JAA member states, passing the tests there and applying to change those foreign issued JAA medicals back to UK issued ones.
So they slammed the door closed on it and will now only exchange a full JAA CPL complete with medical certificate from another member state for a UK issued JAA CPL plus medical (at which point you are only expected to undertake the Class 1 RENEWAL medical, which does not include the CVD tests - what they're doing I think is absolving themselves of any legal liability by slopey-shouldering the responsibility on to the original testing State of Licence Issue). Let's face it, that's what they are far more interested in these days than actual, real safety issues.
Of course, you can exchange the medical without having completed a CPL or the ground studies but it is now a little more than an administrative exercise and if you wish to simply exchange the medical they will require you to undertake the EXTENDED Class 1 medical which DOES include the CVD tests.
Windforce, I'm not quite sure exactly what you mean - could you be a little more specific, please?