With Alton knowing a win would take them within a point of promotion, they started determinedly.
Romsey packed their defence and so were a tough nut to crack, with clear chances hard to come by.
Alton continued to build pressure, with half-chances falling to Samuelson, Compton, Steven and Wilson (junior).
In the last seconds of the half, the Romsey defence was breached, with a well-worked short corner resulting in Wilson (junior) slotting calmly past the keeper.
The second half started well, with Alton continuing to make chances.
A second goal soon came, with a well-worked move between the Wilson brothers allowing Wilson (senior) to find the roof of the net.
Compton then followed up a Samuelson short corner and cleverly flicked the ball past the keeper to make it 3-0, but Romsey never gave up - and their younger legs started to drive Alton back.
Keeper Vincent was called into action a number of times, including making a brilliant stop at the top of the D.
Romsey grabbed one goal back, but Alton closed out the game to finish deserving winners.