After a moreale-boosting 4-0 home win over Wokingham in the Berks & Bucks Senior Cup on the Saturday, United slipped to a disappointing defeat in the Southern League Cup 2nd Round Replay.
The Ducks had enough chances to be three or four up in the first half, but were made to pay on 30 minutes when Dennis Benskin headed in Gulson's deep cross.
Grantham were quick on the break and apart from a brief spell in the second half never really looked like losing and sealed their place in the next round on 70 minutes when Norris chipped the defence for Gulson to run on and score.
