Terrible shame RM that this occurred to you, just glad you are OK!
It must be noted here that metal fatigue can happen at any time, & I would urge all owners of 'older' doubles to get there barrels x-rayed for any inclusions - before it happens!
To come back from one of these instances is a real credit to yourself mate, you have given this old lady back her legs & preserved her for at least another century.
Your mate certainly did a wonderful job.
All the best in the field with your 'old girl'
Cheers
93x64mm