The Herbs and The Adventures of Parsley   Classic BBC kid's animation by Michael Bond

On this page ..... A set of colourful greetings cards -complete with a Letraset novelty bonus
These all carry a 1973 copyright mark,and measure 22 cm x 11.5 cm
There's nothing to say how many different ones were available.
But I'm very confident this is the full set,even though the rather glaring omissions of the likes of Sir Basil and Constable Knapweed might lead you to think otherwise.

Produced by a company called "Personal Cards".With the "Personal" gimmick being that you had the choice of "over 370" christian names in the form of a rub-down transfer that you simply applied as appropriate.
One name was included in the card price of 18p,but had to be chosen from a display at the point of purchase as it was clearly wasn't feasible having all 370 bundled inside every card. 
Although each card did have a small sheet of number transfers from 1 to 9 inside,so you could add the appropriate age. And it's no surprise that both the names and numbers were printed by Letraset -who else in the 1970's ?!
All of which could either be seen as a bit of fun or an unnecessary pfaff I suppose.

Inside,each one is blank apart from a refreshingly simple "Many Happy Returns",resisting any attempts at some rather obvious "Herbidacious" wordplay.Which is completely in keeping actually because, gimmicks aside, they're quality items,with nice artwork and lovely crisp printing.
Certainly worth 18p of anyone's money I'd have thought.
Although,like most of the merchandise,it's impossible to know how well they actually did.