I used a 4&1/2" leg vice I bought form G & S Holloway for 39 years for most of my work.I also had a 5" leg vice used on the barrel bench .Before that I used leg vices of similar size for all my time at W & S . Additionally for very occasional use I had a 4" engineer's vice .

If only one was allowed the 4&1/2" leg vice would have done for me .