In days gone bye if the dreaded 'A' word was even whispered at Biggin Hill you were out the door so fast your feet didn't touch. These days still a no-no for any trade involved in parting company with terra firma.
Some ground trades are available but you MUST show proof of a lack of recurrence in I believe the 5 years preceding your application. The proof being that no prescribed drugs have been used, no visits to GPs and for deffo no trips to A&E for anything to do with the dreaded 'A' word.
So, if you've had a prescription for Salbutamol/Ventolin, Becotide etc. in the last X years, forget it. The RAF Band won't even have you to hit a bum note on a base drum!
I recall the reason for this almost blanket ban was due to guys who had grown out of their childhood asthma being Medevac'd out of the Falklands after not having had an attack for decades in some cases. A combination of stress and climatic conditions was to blame but the seeds were sewn which have resulted in the continuing policy.
Speak to the powers that be for a definate time-scale, but I'm sure its in the 5-10 years bracket.
Rgds
T3