My last reply was lost in the forum crash/update so here's the Whitworth links again -
Whitworth sockets and spanners -
http://www.baconsdozen.co.uk/tools/whitworth.htm
big 3/4" drive and 1" drive whitworth sockets -
http://www.lawson-his.co.uk/scripts/products.php?cat=King%20Dick%203%2F4%22%20Drive%2012%20Point%20Whitworth%20(BSW)
http://www.lawson-his.co.uk/scripts/products.php?cat=King%20Dick%201%22%20Drive%2012%20Point%20Whitworth%20%28BSW%29