1962 or 1963? Does it really make a difference? Perhaps! Perhaps not! But it's one of those uncertainties (like the year Paul Ysart actually left Caithness Glass) that arises out of differing "facts" from various literature and personal comments.
Taken together, the various entries in websites and books give an unclear idea. Some references give an explicit year of 1962 and others, 1963. At least one reference, based on Paul Ysart's stated age at the time (61), gives a deduced year (from his date of birth, June 1904) of either 1965 or 1966, which is too late and suggests a probable misprint of his age!
From certain references, I am beginning to think that the actual date of Paul's move may have been late in 1962 and perhaps as late as December. However ...
... as Frank says, the year 1963 came from Paul himself. As well as being given in the Ysart Glass book (1990), that date was also stated in the catalogue for the British Glass Between the Wars exhibition at Broadfield House Glass Museum in 1978.
Also, I have a CD of a set of taped interviews with Paul Ysart which were recorded in 1978 in preparation for a book on Scottish glass but which never made publication. On the tapes, Paul said that he started work, with his father, at Moncrieffs in Perth in 1922 and on two separate occasions he stated that he was with Moncrieffs for 41 years - suggesting the move to Caithness Glass at Wick was sometime in 1963.
I shall try to contact Peter Holmes to get confirmation of some of the "facts" reported.