Good topic. I found it a bit tough to shoe horn enough English and Scottish players in, so those selections are slightly more questionable (although I fail to see why Duckham doesn't get more love). In hingsight, I've placed a lot of emphasis on longevity and success and know little to nithing about rugby before the 70s.
1 Ian McLauchlan
2 Keith Wood
3 Fran Cotton
4 Gordon Brown
5 Martin Johnson
6 Richard Hill
7 Fergus Slattery
8 Mervyn Davies
9 Gareth Edwards
10 Barry John
11 David Duckham
12 Mike Gibson
13 BOD
14 Gerald Davies
15 Andy Irvine