I have written to the Transport Minister on behalf of the 15 Liberal Democrat councillors in Lambeth, urging her to ensure Thameslink services continue to run north of Blackfriars to St Pancras International and Luton airport.

The service is very heavily used by residents in Streatham, Tulse Hill and Loughborough Junction to take them to work in the City, and for business and leisure travellers to access onward connections at St Pancras International and Luton Airport.

It also offers the opportunity to connect with Crossrail at the new Farringdon interchange providing easy and fast access to the West End and the City.

Streatham has long been promised an underground connection – in the form of an extension to the Northern line – but this prospect has been foreclosed by the recent endorsement by Lambeth Council and Transport for London of a developer-led extension to Battersea.

Other suggestions of an extension to the Bakerloo and/or Victoria lines have also failed to materialise.

The through Thameslink service is, therefore, the nearest equivalent of a fast underground service that residents in the south of our borough have access to, and will continue to be so for the foreseeable future.

It would be unacceptable for our residents to find themselves cut off totally, while passengers from Brighton benefit from 24 trains an hour.

This level of service must surely put the capacity of the fast line at risk in any event, and is unjustifiable if it means people from our area will get nothing at all.

We are not at all comforted by the suggestion a potential change of train at Blackfriars for passengers will be made simple.

For those who have mobility difficulties, or carrying heavy luggage, or accompanying young children, any change is a difficult change.

And for those who simply have to use the route from Streatham, Tulse Hill and Loughborough Junction to get to work, a daily change at Blackfriars is another point at which their journey will be put at risk of delay.

It is clear the more legs a journey has, the more chance there is of a missed connection, and some associated inconvenience.

A through service from the “Wimbledon Loop” is a requirement in the specification for the Thameslink franchise.

Streatham Hill councillor Ashley Lumsden, Group leader of Lambeth Liberal Democrats