Guy and LFJ have been saying across several threads recently that Wong Shun Leung taught that the Tan Sau motion was only for training the elbow for the punch and is not to be used as a defensive technique. Now I'm starting to wonder if WSL really taught that! They say "a picture is worth 1000 words." A quick google image search turned up these:
http://practical-wingchun.com.au/media/422085_447610705332391_2014558204_n1-256x300.jpg
http://ewingchun.com/sites/default/...le-images/attilio-reale-wong-shun-leung-4.jpg
https://cranesproduction.net/images/WSL web.jpg
http://practical-wingchun.com.au/media/422085_447610705332391_2014558204_n1-256x300.jpg
http://ewingchun.com/sites/default/...le-images/attilio-reale-wong-shun-leung-4.jpg
https://cranesproduction.net/images/WSL web.jpg