Gerold
Having had a word with Angus Primrose's wife Murlo, I can tell you that what you read, that 'all Primrose-designed yachts had a primrose symbol in a horizontal line on the hull', is not strickly true. Certainly she recalls that the older Moody's had this line and symbol but not that all the boats he designed had it. Certainly I have not seen it on any of the Seal yachts (though some may be found), and Murlo does not think any carried it.
Regards
Don
Don Harvey