Lewisham's mayor has vowed to make all the council-controlled roads a 20mph zone.
Speaking at the council AGM, Sir Steve Bullock told newly-elected councillors: "We will build on the success of our 20mph zone programme by making the whole borough subject to a 20mph limit.
"To make that work we will need to change the mind set of drivers so that 20mph becomes the default speed.
"We will only succeed in doing this with the help of the police and the GLA."
Campaigner Clare Griffiths and the Green Party's Darren Johnson handed in a petition back in April calling for the mayor to introduce the 20mph zone, citing the example of nine other London boroughs which have the policy.
Elsewhere in his speech, Sir Steve called this term "the most challenging four years this council has faced for a very long time" with cuts of £95m on the way.
He went on to promise more affordable housing, increase school places to meet demand and lobbying for a Bakerloo Line extension to the borough.