Interview: Philip Dunne, UK Defence Equipment, Support and Technology Minister 12 Jul 2014 Andrew Chuter
Quote:
"...Q. Britain launched the first of two new aircraft carriers July 4. As things stand, SDSR will decide whether the second warship goes into operation or is mothballed. What’s the department’s current view?
A. It’s really a Royal Navy decision. With the capability procured, it’s a matter of crewing and sustainment.
I know the First Sea Lord [the head of the Royal Navy, Adm. Sir George Zambellas] has expressed his preference for two carriers, as has [Defence Secretary Philip Hammond], but it will be up to the Royal Navy to find the budget to be able to crew two vessels for rotating deployment. It’s an operating expense rather than a capital expense. The issue is not to have two carriers on station at one time but to enable a continuous presence...."
Interview: Philip Dunne | Defense News | defensenews.com
So what the Defence Secretary is saying is that if the RN can afford the crews from their current resources then they are free to have both carriers but HMG isn't going to increase the defence budget to suit.