Arguments that lives will be put at risk on flights with volunteers really do not stand up. The volunteers will be completing a training course to CAA approved standards, of varying length depending on their current level of knowledge and experience.
Pilots courses will be short, a full day of self study and 3 days in the classroom. This is because we already know a lot of the SEP stuff. We do SEP every year. I think we can be trusted to use a BCF on an oven fire, handle pilot incapacitation or 'take command of a life raft' without any further instruction. Why has no comment been made on the added safety benefit of having a couple of spare pilots down the back?
As for the comments that a passenger would have died without the specialist knowledge an experience that only BA crew can bring, firstly all cabin crew are trained in these procedures, so if you had a heart attack on a a virgin flight the same would apply. To suggest otherwise is offensive to other cabin crew.
Secondly lets look at the fact shall we - CPR and operating the Defib 'saved' this person (against the advice of a highly trained specialist doctor). How long does it take to learn these two skills? How much 'extra experience' do the majority of BA crew have in using the defib or administering CPR, outside of their yearly SEP refresher?
The passengers on BA flights crewed by volunteers will be safe. They may have to accept an inept and slightly amateur service, but they will not be at any risk.