 The Commandos were aided in their planning for the operation by Captain Bill Pritchard of the Royal Engineers , who had pre @-@ war experience as an apprentice in the Great Western Railway dockyards and whose father was the dock master of Cardiff Docks . In 1940 while part of the British Expeditionary Force in France , his duties had included determining how to disable the French dockyards if they were captured . One of the dockyards he had studied was St Nazaire , and he had submitted a report detailing how to put the dock out of action . 
 The Commandos <a href='uninflect' title='1'><mark>were</mark></a> aided in their planning for the operation by Captain Bill Pritchard of the Royal Engineers , <a href='null_relcl' title='2'><mark>who</mark></a>had pre @-@ war experience as an apprentice in the Great Western Railway dockyards and whose father was the dock master of Cardiff Docks . In 1940 while part of the British Expeditionary Force in France , his duties <a href='been_done' title='3'><mark>had</mark></a> included determining how to disable the French dockyards if they <a href='uninflect' title='4'><mark>were</mark></a> captured . One of the dockyards he <a href='been_done' title='5'><mark>had</mark></a> studied was St Nazaire , and he <a href='been_done' title='6'><mark>had</mark></a> submitted a report detailing how to put the dock out of action . 
Da Commandos was aided in their planning for tdaoperation by Captain Bill Pritchard of the Royal Engineers , had pre @-@ war experience as an apprentice in the Great Western Railway dockyards and whose father was the dock master of Cardiff Docks . In 1940 while part of the British Expeditionary Force in France , his duties done included determining how to disable the French dockyards if they was captured . One of thdaockyards he done studied was St Nazaire , and he done submitted a report detailing how to put the dock out of action .