Rear caliper bolt problem

[Clifford Pope]

Problem solved, but I'd nearly given up and was wondering what was left to try.

The handbrake had been getting poorer over the last year, and finally despite tightening the adjuster to the maximum extent it failed totally.
An inspection of the nearside brake shoes showed there were no linings left, so I replaced them, after a bit of a struggle getting the bottom spring back on and the shoes centralised and not binding on the drum.
The brake worked well - better than I've ever had a 240 handbrake work, but I thought I'd better check the offside just in case.

All the previous caliper bolts have been tough to undo, but one the one remaining was impossible to budge. There is no space because of the road spring to get a socket on it. I used a well-fitting ring spanner, but the bolt head simply deformed and the spanner slipped. I tried another spanner. I tried to force on a slightly smaller spanner from an AF series, but that slipped too. The head was now rounded, and there is no space for a wrench.

Finally I removed the road spring so I could get proper access, and hammered on a smaller socket. It was very tight, but I kept on belting the socket and got it properly on as far as it would go.
It was touch and go. I could feel the metal beginning to deform again, but suddenly it moved, and the bolt was free.

It was worth doing - the shoes were of course completely worn out too.

So my question is, what ought I to have done? What's better than a ring spanner in a restricted space?
Supposing the bolt had rounded again - how is it even possible to get the stub cut so that the caliper can slide clear? Drill it out, somehow? Take the car to a garage - to do what?
Buy another rear axle?

Any thoughts anyone? (Obviously I'd already tried soaking in Plus Gas, and playing a gas flame on it)