I am fortunate to possess Vols I and II of "The Cutty Sark" by Dr C Nepean Longridge, who also wrote "The Anatomy of Nelson's Ships", both books describe the detailed building of models of Cutty Sark and HMS Victory respectively, both of which presently reside in the Science Museum at South Kensington, London. The former book published c.1933, has long been out of print and no-one, to my knowledge, has ever reprinted it - goodness knows why!! G.S. Laird Clowes the then director of the Science Museum said that Dr. Longridge "has that priceless combination, for a maker of ship models, a mind well trained to inquire... he insists first in finding out and checking each individual detail, and then in reproducing it correctly."
Dr. Longridge had the advantage of going aboard Cutty Sark whilst it was moored at Falmouth (since 1922), having been bought in Lisbon, by Captain Dowman to save it from the same fate as befell Thermopylae. I believe that it was the Captain's widow who presented it to the Thames Nautical Training College to act as an auxiliary to HMS Worcester. In 1950, Worcester was replaced by a larger vessel and Cutty Sark was no longer required; she was offered to the then London County Council (now the GLC) who believed that this old vessel should be preserved for the nation. The Cutty Sark Preservation Society was set up in 1952 and a public appeal was made. The rest you know.
Now for the mizzen pinrail. On page 190 of Volume I of"The Cutty Sark" Dr. Longridge writes "Under the mizzen rigging there is a small rail with five belaying pins 1 1/4 in. long , 3/16 in. wide, 11/16 in. high, (these are 1/48 scale measurements - my insertion) supported on two turned legs painted white. As there is only a spider band round the mizzen, with eight pins and no fife rail at its foot, obviously more places are required for turning up the mizzen rigging together with the main topgallant, royal and skysail braces, not to mention the spanker gear. It is, therefore, reasonable to suppose that this small pin rail was at some time substituted for a much larger one, and I have made them (the pin rails - me again) to run from the topmast backstays aft for two in., (in 1/48 scale this would be 8 feet full size - me) and given them ten pins a side."
In light of Laird Clowes' obvious respect for Dr. Longridge, born of "many interesting talks", I believe that the good Dr is probably correct, remembering that the ship - whilst in Portugese hands - was rigged as a barquentine. I should point out here that the Cutty Sark, as it was until recently, is not wholly accurate either in terms of its deck fitting, nor rigging and displays items and details from several different eras of its existence. George Campbell's drawings, which were prepared, officially, for the preservation of the ship, were condensed from about sixty others which explains why they are so cluttered. I respectfully suggest that the rigging could be reconstructed using a combination of George Campbell's plans and a copy of Harold A Underhill's "Masting and Rigging the Clipper ship and Ocean Carrier". Together these will provide all that the modeller requires. The book is published by Brown, Son and Ferguson, Glasgow, Scotland. My copy has no ISBN.
Mr Campbell, incidentally, was not overly enamoured of the Revell kit - "there is an awful lot missing and incorrect in the kit which is inevitable when a manufacturer decides to over-simplify for the sake of mass production. I do not mean to detract from the kit which is an excellent job in other ways." This observation was written 45 years ago, when plastic models were built as bought and rarely modified. Given the very basic questions about rigging that I asked, I believe, he was concerned that I might sdimply give up should I attempt to make the kit an accurate depiction of the vessel. I now believe he was hinting that, with the necessary effort, it was a basis for a good model, but not as bought, which is surely what modelling is all about. Revell used Mr. Campbell's drawings to produce their kit. Sorry for the length of this note, but I hope it is of use. Difficulties are challenges not obstacles. Good Luck. Flitch