The double champion from the Bentham club near Cheltenham was defeated 21-13 by Nottingham's Brett Morley, whom Allcock had defeated with Mervyn King in the World Indoor Pairs Championship final at Preston in February.
Allcock thought he had ended his Melton Mowbray jinx earlier this week when he won an English title there for the first time. However, yesterday it seems to have returned.
Morley showed his victory was no fluke by defeating Carlisle's Paul Barlow 21-16 in the second round to reach the quarter-finals.
His opponent there will be Blackpool's David Holt, who defeated the English outdoor singles champion, John Ottaway, from Wymondham Dell, Norfolk, 21-14 in the second round.