Both Gary Phillips and Michael Danzey were ruled out through injury, and on 16 minutes Phillips' deputy Andy Hopping was beaten by an unmarked Southon header.
After 22 minutes a collision between Hopping and Charles caused a lengthy delay which ended with Hopping leaving the fray and Carl Hoddle taking over in goal.
Apart from Kevin Davies having a shot kicked off the line by Billy Goldstone on 37 minutes, United rarely troubled keeper Capleton in the half.
Grays went two up on 64 minutes through Wilson and this woke United who created numerous chances thereafter. Robert Sharpe, Peter Scott and Matt Hayward all went close, but yet again United returned from Essex pointless.
Grays Athletic
Aylesbury United
Bromley
Yeading
Carshalton Athletic
Boreham Wood
Chertsey Town
Enfield
Dagenham & Redbridge
Staines Town
Dulwich Hamlet
Heybridge Swifts
Hendon
Bishop's Stortford
Hitchin Town
Harrow Borough
Kingstonian
Yeovil Town
Oxford City
Purfleet
St. Albans City
Sutton United