The comments on Harrier and Tornado capability are on the mark, but I think the OP’s question is one of finance. The situation described was ‘ops normal’ for MOD in the 2000s, which is the only period I can speak for - it may have been true earlier. Unaffordability of each year’s programme was routinely dealt with by punting costs into later years, which worked for long enough to get 1* and 2* tours safely complete until 2010, by which time the whole edifice was on the point of collapse with a wave of expenditure that could be delayed no more, forcing radical decisions to cancel. Borrowing to fix it would have effectively endorsed the poor behaviours that got us to that sorry juncture. From the vantage point of almost 10 years on, SDSR 2010 simply forced some decisions that should have been taken years earlier... and I include binning of MRA4 in that. We wouldn’t have needed to have endured a decade-plus capability gap if that decision had been taken earlier.
Regrettably, things don’t look too dissimilar now.