Unfortunately, although we live in a relatively threat-free period at least in terms of military threats, intentions can and do change quicker than we can change capabilities. There are too many potentially hostile nations with force levels we could not contend with at present. Although in the past we have generated improved capabilities quickly in time of tension, modern technologies and the ability to use them preclude the rapid expansion that our small force would need.
So are we content to be a small part of a large coalition or do our politicians want us to be able to influence world events as UK PLC?
It appears that they want the latter with a budget more suited to the former. As usual, they live in cloud cuckoo land but are the military chiefs telling them that?