The account in "Last of the pirates" may well be incorrect with regards the early stages of the build, but Bob Noakes was obviously there for the completion.
On page 247 of the first edition of the "Bible" states, "The work had to be carried out at sea but riggers would not come out so it was done by a small group of engineers and djs', Norman, Peter, Dick and Robin.
Whereas the softback states on page 252, "The work had to be undertaken at sea and a team of professional riggers were used" but ultimately after an incident left the Caroline guys to finish the job.
I tend to go with Bob Noakes' version in Last of the Pirates which aligns with my original post, ie the mast was built at sea by Norman, Robin etc.