Well the mid '50's did have Russia on the doorstep, we were building the H bomb, buying THREE types of strategic of bombers, running a load of carriers, still had an Empire which we were fighting in and also had loads of National Service personnel to train and feed
Not surprising it was expensive
Comparing it to Welfare is a bit of a red herring - unless you are willing to go back to the standards of care and medicine of the mid-50's as well
Also remember tax rates then were twice what they are now
Undoubtedly we need to spend more on defence right now - but unless and until people are willing to pay more tax it's tough to do if you want to be elected