Colonel Forster responds to Lydia's disappearance with humane urgency, but his search loses the eloping pair on the London road.
Colonel Forster learns that Lydia Bennet has left Brighton with one of his officers, Mr. Wickham, and immediately sends an express to Longbourn. When Mr. Denny's warning casts doubt on the story that they are heading to Gretna Green, Forster leaves Brighton to follow them himself.
He traces Lydia and Wickham to Clapham, where they leave the chaise from Epsom for a hackney coach and disappear toward London. He continues inquiries at turnpikes and inns through Barnet and Hatfield before going on to Longbourn to disclose his fears with the greatest concern for the family. Jane judges him and Mrs. Forster free from blame, though his return to Brighton is urgently required the following evening.
The text identifies him as a colonel but gives no description of his age, face, hair, complexion, build, uniform, or dress.
He is the conscientious officer who acts quickly after Lydia's flight, even though his search cannot recover her.