Angry commuters have started a petition against plans to scrap train services from Tulse Hill, Herne Hill and Loughborough Junction to central London.
They object to plans by the Department for Transport to terminate trains on the Wimbledon Loop at Blackfriars station by 2018. The trains currently run through the city to St Pancras and beyond but rail bosses say congestion on the line means they may have to cut services as part of a new franchise.
Anyone who objects has until August 23 to respond to the consultation.
Commuter Cath Malone said: “This is an incredibly cynical decision to terminate the Wimbledon Loop at Blackfriars.
“Thousands of us commuters use City Thameslink and, more recently, have found the wonderful convenience of linking up with St Pancras. Just when we were getting some improvement to our service, having put up with dreadful overcrowding and poor service for years.”
Chuka Umunna, MP for Streatham, appealed to members of the public to respond to the government consultation.
“It is essential that we all act together to retain the links between Streatham, the City and North London,” he said.
“It is incredibly important for the convenience of everyone living here, as well as our local economy and the job prospects for local residents.”
A spokesman for the Department for Transport said: “This is a consultation document and we welcome any views on the best option to take. We encourage people to provide responses.”
To object to the changes email firstname.lastname@example.org, and sign the online petition here.