Last week we ran a story under the headline “Could London get a new tube line from Canary Wharf to Euston?” In it, editor Jonn Elledge reported news that the Canary Wharf Group had submitted plans to the government for a new rail link from their expensive set of office blocks to Euston station, to prepare for the arrival of High Speed 2.

Jonathan Roberts, a transport consultant and contributor to the excellent London Reconnections, got in touch with his thoughts on the matter. We present them, lightly edited, below…

There is ‘previous’ for a Canary-Euston link. The Waterloo-Canary express tube – really a ‘Drain’ [like the Waterloo & City line] to Canary, rather than to the City – was transmogrified into the Jubilee Line extension, and ended up being largely funded by others.

However, this time think of the original Waterloo-Canary-Greenwich Peninsula limited stop express tube scheme, and realign so it is Euston-Canary limited stop express tube. I’ve noted the interest of the London Borough of Southwark, and also the distance – 8.5km – stated in New Civil Engineer.

From South Dock to the far side of ‘New’ Euston in a straight line is 9.25 km (5.75 miles).

From fully alongside Crossrail North Dock station to the far side of ‘New’ Euston is 8.95 km (5.55 miles).

From fully alongside Crossrail North Dock to a double-ended Euston-St Pancras (under the Euston Road in this instance) is 8.75 km (5.42 miles).

From a shorter North Dock station to a double-ended Euston-St Pancras is 8.5 km (5.28 miles).

That could serve all Euston trains, Thameslink, St Pancras and all Kings Cross trains.

What’s the journey time at 50-60 mph average speed? About 10 minutes if no intermediate stops. However, Old Street or Spitalfields might be very interesting as new connectivity and new sources of local travel, at the cost of a longer overall journey time.

But an 8.5km scheme could run from the South Dock to a station terminating at Euston from the SE – passing close to or under Farringdon, and under the City.

So there are several interpretative options, depending on whether or not there might be intermediate stops and precisely where those might be (and how you might route it to avoid tall City buildings). Some options:

Click to expand.

Definitely a scheme to watch.

Oh, we will.