For those who may be interested.
I managed to get a GP letter confirming my history of childhood asthma and the last recorded prescription etc. They were still reluctant to issue me with my records so against the advice of the AeMC I asked for the medical to be deferred to the CAA with the GP letter alone and without doing the exercise Spirometry.
Within a week I had received a letter from the CAA and they have issued me with an unrestricted class 1 medical.
This therefore confirmed my suspicion that the test was not required so this saved me around £345, plus a day off work and a 400 mile round trip.
I will not name the AeMC because they believe they were following the correct guidelines set by the European Union but it goes to show that sometimes it’s worth questioning your AME if you believe something isn’t quite right.