I'm a new member living in Belgium and I thing I can help on this: Craddock is the name of a quite old (around 1980 or earlier) Belgian fly still used today as a wet fly in rivers and occasionally as a streamer (i.e. lure) in rivers and ponds. I am not fishing it often - actually I am not using it at all nowadays - but there are still some "old hands" here who consider it an essential pattern especially in the early season, March and April. There are many variants, to an extent that I am not able to tell you what is the "true" original formula; considering the level of fly fishing literature here in the eighties I wonder if a formally "true" pattern has ever existed. As mentioned in the website of the Royal Casting Club de Belgique, it originated on the river Ourthe, devised by local fishermen whose names are in part lost in time. It was popularised by Marc Reckinger and Raphael Courte.
The page given by FLdk is the only one where I found one of them on the web, I add here a couple of photos of different versions taken from the Belgian fishing magazine “Pêcheur Belge”. The photo in the webpage of RCCB is odd for two reasons: tail is missing, and head is black; a regular feature that I have always seen in every Craddock is the brilliant RED colour of the head (I am told that some use a BRIGHT GREEN head as well).
The EN translation of the formula provided by the RCCB does not match their own French text exactly, here a better translation
Hook 6 to 12
Body Peacock herl
Rib Golden tinsel and red thread
Hackle Brown partridge hackle
Tail Brown partridge (optional)
Source Wet fly invented by the Ourthe’s fly fishermen (this is not, of course, the title of a book)
Use Used in early season, as point or bob fly. It is also very effective in closed waters.
There are many variants: the brown partridge for the hackle can be replaced by grey partridge, grouse or mallard fibers, the hackle can be tied “wing style” (as in one of the annexed photos), for the tail some use pheasant or mallard fibers, and silver tinsel for ribbing.
Best regards to all,