It is assumed that they will be providing an MD902 because that is what they [MAS] operate now. It mentions two but does not yet explain what 'two' is. Is that 2 aircraft 24/7/365 or some other permutation? It may simply be a guaranteed aircraft during downtime [but I think not].
There are no NEW 902s available with an enhanced spec before 2015 [if then].
There may be other second hand 902s available for the company to acquire.
SAS/PAS/MAS has ordered AW169s but they are significantly larger than most current air ambulances in the UK.
I would expect it will come obvious in time for the launch day.