Nicholl’s first try came from full back Roger Sevier’s cross kick, with the latter converting.
Maidenhead replied with a penalty before centre Henry Day’s kick set up a similar second try for Nicholl, Sevier converting for 14-3.
The visitors bagged a converted try before Sevier and Maidenhead’s kicker slotted traded penalties.
Day’s run ended with fly half Nick Sevier scoring Grove’s third try.
Nicholl converted from the touchline as Roger Sevier had gone off injured.