I got mine from Marc Anthony cycles in Buxton.
Hard to find. I bought some donkeys years ago from Harry Halls in Manchester, and already then stocks were thread bare.
You need to know the year - front, DS and NDS are not exactly the same length if I recall correctly without going into the attic to check.
In all fairness though, these were very much a re-defined very very high end and über expensive race day wheelset with longevity over many years never in the design equation.