Islington Council is “ready for a stand-up row” with Transport for London (TfL) over its bid to become the first council in the capital to introduce a 20mph speed limit on main roads.

The proposal – agreed by the executive last night (Thursday) – would see the speed cap brought in on “principal” roads such as Essex Road, Blackstock Road, Hornsey Road and Caledonian Road.

But the council’s Executive member for planning, regeneration and transport said he fears TfL could put the brakes on the scheme, which it has to approve because some of the roads form part of its “strategic road network”.

Cllr Paul Convery said: “I am hoping they will not get in the way but there’s a real possibility they will block it. If they invoke that power, we will have a real stand-up row. We are ready for that row. There’s a high chance of a child or older person being killed if they are hit by a vehicle travelling at 30mph, but at 20mph it’s almost certain they will survive. I think we’ll be the first in the UK to do it.”

The council hopes new signs will be enough to slow motorists down. It will not build speed bumps and police will not enforce the limit, just as they do not the 30mph maximum, or the 20mph cap in place on residential roads.

The proposal has been welcomed by safety campaigners and hailed as a huge boost to a growing campaign to cut speeds to 20mph across the capital.

Caroline Russell, chairman of Islington Living Streets, said: “It’s marvellous and let’s hope that Islington can show the way. The numbers seriously injured and killed on the borough’s roads have gone up in the past two years and this could halt that rise. It will save lives.”

Only the busiest roads controlled by TfL rather than the council such as the A1, Seven Sisters Road and Camden Road will stay at 30mph.

A TfL spokesman said: “TfL has long supported 20mph zones in residential areas, but certain sections of London’s road network are not suitable for 20mph zones.

“The potential for new 20mph limits will vary by area and road type.”