Wolber,
I believe frame 7331 is a 1973 WF Holdsworth, Putney Shop Italia model. Italias were often built by outside contract builders and often for shop stock. (
http://retroride.blogspot.com/2007/05/h ... _1672.html ) Yours may very well be original paint as has usual shop seat stay cap lining. Dave Scrimshaw and I have discussed this style of dating serial in the past at length as well as in other threads and it appears from his data that quite probably outside "Shop" contractors were, as a general rule, using a 2 digit dating code in early 70's where as Roy Thame's main buider Tommy Quick appears to be still using (in 1973) numbers prefixed by 69 and placed along BB edge. Two possible outside builders described by Kilgariff are well respected builders for the "trade" Charlie Roberts and Alec Bird.
If you have an Excel reader and search Dave's data you will see besides factory builds, examples of other shop builds for this period, as well as graphs and prediction table. "Shop" builds are much less common.
https://drive.google.com/drive/folders/ ... TNKZkN4TmM
Doug