Despite heavy rain, crowds lined the streets as the five-time Olympian carried the flame in Southend-on-Sea where he began his swimming career.
The relay was greeted by a 2,000-strong choir as it arrived in the seaside town, home of the world’s longest leisure pier.
Torch bearer Matt Fletcher, who last year donated a kidney to his daughter Hope, and raises money for the Great Ormond Street Hospital renal unit, handed the flame to Foster.
The swimmer was among 138 torch-bearers as the relay made its way along the 117-mile journey from Ipswich to Chelmsford.
John Bowman, 45, the husband of a former Essex Police sergeant who died from cancer earlier this year, carried the torch out of Southend.
His late wife, Kirste Snellgrove, was originally nominated to carry the torch, but he instead carried it in her honour.
He said: “It’s a great honour to be able to carry the torch for Kirste but it will be a difficult day for me.
“When she passed away, the charity wrote to the Olympic organising committee to ask if I could carry it in her memory.
“I know how much Kirste was looking forward to carrying the torch so it’s really fitting that I’ll be able to carry it for her.”