A size 50 Monarch A2 is a rare beast indeed. Monarch A2s tend to fit small compared with most other makes and the chest on this one is only 46". Nevertheless it should do well. Shame its not a 46 or 44 as I would have been interested.
http://cgi.ebay.co.uk/WW-II-Flight-Jack ... 0283168370
http://cgi.ebay.co.uk/WW-II-Flight-Jack ... 0283168370