Thanks Gizzy and and all who replied. I have tried to get the amber off the bulbs I have, but not very succesfuly!
If anyone has not followed the discussion started by Gizzy's reference to Bevercreek, you should. These LED lamps seem to be the perfect answer. The 10 on offer on German ebay look like a good deal to me (I do like their no hassle potential - plenty of other problems to solve!).