'would never happen...'
HA! We hope...
NB: UK PLC is quite capable of funding a large Army (150 000) Navy (at least 50 warships FFS) and Airforce (significant whizzy stuff, big stuff and whirly stuff), we should not even be asking this question - what we SHOULD be asking is how we can fight the trend and get funding back up to what it should be at - IMHO, somewhere around the 1960's spend.
People say we're broke, theres no more money, well no, there isn't, but that is a symptom of where we are putting the money we have (and in all fairness compared to most of the rest of the world, we have an awful lot)