The hosts eventually took the lead in the 54th minute when Cliff Hercules picked up a ball infield, beat one man with a turn of speed and was in the process of beating another when he was pulled down in the box by Tony Powell and Dave Sansom sidefooted the resulting penalty past Leyton keeper Graham Poultney.
It was 2-0 in the 64th minute when Junior Wilson's quickly taken throw in on the left found Sansom who controlled the ball on his chest and turned, swivelled and crossed in one superb movement for Hercules to beat everyone to the ball at the far post and head past Poultney.
It was 3-0 in the 72nd minute with an equally good goal when Allan Pluckrose outsprinted the visitors' defence down the left from the halfway line before rounding the advancing Poultney and tucking the ball home.
United could have won by a far greater margin but they would have been happy enough just to get their season off to a winning start.
David Figg