Already denied certain victory by the elements at Swansea last month, Northamptonshire's hopes of closing the gap on the Championship pace-setters were doused by similarly inhospitable conditions that restricted play to 23.4 overs.
In a so-far one-sided contest between two of the four counties who have yet to win the pennant, Sussex finally found something to cheer in the second over when Nigel Felton, having added a single to his overnight 108, attempted a leg glance off Adrian Jones and walked when wicketkeeper Peter Moores claimed the catch.
With Lamb anxious to improve upon a modest first-class average of 26.63 and a season's best of 64, the visitors quickly recovered their poise. Lamb collected nine more boundaries to reach 60 as Northamptonshire reached 447 for 6 by the close.
Essex expect to announce on Monday how much they have fined their fast bowler Neil Foster for kicking down the stumps in anger at Old Trafford on Thursday. Essex's secretary, Peter Edwards, said: 'If such an incident had happened at Chelmsford we would have resolved it straightaway. I have spoken with Graham Gooch and we will be taking action.'Reuse content