I think someone mentions on the Sheffield thread that David is coaching Gledden so i'd expect it's the only reason he's playing. His last update on his site over a year ago expressed his intention to retire and concentrate on coaching.
Used to use the top 500 table all the time to keep up to date before I stumbled across firstly the Rusedski message board and then this one.
Nice to know someone used the top 500 table on the Sherwood site (one of its many 'syndications' LOL) - David's based in Sheffield and, as you say, coaching Gledden, so everything points to it being a one off.
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GB on a shirt, Davis Cup still gleaming, 79 years of hurt, never stopped us dreaming ... 29/11/2015 that dream came true!