If two carriers were going to cost £5 million, I think we'd look to expand the fleet a bit more.
I don't believe they're being built at one shipyard - the work is being split between several yards.
Really this is down to the government not putting the facts down on the table early enough. It was happy to say that money would be saved (in the short term) by delaying the build, but it probably knew that in the long run the cost would be higher. Doesn't mean the project is suddenly unaffordable.
If the project goes ahead I doubt there will be a "very lengthy" delay because it will just cost more again (and in a way that it's more expensive in the short-term too). A significant delay on top of the revised schedule would almost certainly mean cancellation.
However, at the moment I'm sceptical of this latest doom-and-gloom report - there have been a number in the last few months. Fact is that the contracts have been signed (who wants to bet that there are no penalty clauses?), £1 billion is soon to have been spent and the project has survived so many attacks on it by the other services, armchair generals (whose mantra of "the wars of yesterday are gone" always get proven wrong every decade or so) lefty hug-a-Taliban brigade and friends that it isn't facing anything new.
Keep an eye open in the next few weeks, as steel is/was due to be cut soon.
Sampan, I'm not surprised that Sir Michael Jackson would say that (sadly there's little service solidarity at the moment thanks to the Treasury). As for Portillo, I'd like to see him suggest to Liam Fox in person that the future Defence Secretary cancel a partly built aircraft carrier! But I think a defence review after the election is likely to work out what the country needs, how it would be best acquired (possibly more off-the-shelf purchases) and how much it will cost.