[Macbow]

Perhaps not exactly what you're after but you could try these - you'll need the Rain Vane Magnums which you could cut down a bit. Not in the UK but available to the UK
Bi-Delta Vanes & Archery Products Vane Model Page,Bi-Delta 2.5" Shark's Tooth,Bi-Delta 4" Rain Vane Feather-Like,Bi-Delta 4" Shark's Tooth,Bi-Delta 4" Jet 35,Bi-Delta 3" Hyper Delta,Bi-Delta 4" Hunter 3-D,Bi-Delta 5.3" Mangnum Bee.