The firm has just completed the 18-month first stage tunnel drive for the £100m gas transportation project slightly behind programme.

Now preparation work is getting underway to attempt the challenging pipe-jacking feat.

This will involve painstakingly pushing eight, 610m sections of pipe at about one metre a minute through the 5km tunnel.

Before the two hydraulic thrust machines start the epic task next spring, the team must first dismantle the 3.65m diameter TBM Mary.

Steve Ellison, lead project manager of Capital Delivery at National Grid, said: “It’s the first time a tunnel has been constructed beneath the River Humber and a fantastic achievement for everyone involved.

“Over the next few weeks we’ll be dismantling the tunnel boring machine and lifting her out of the ground in sections, ready to be transported back to Germany, where as much as possible will be refurbished and renewed to get her ready for her next tunnelling job.

“The next steps for us here under the Humber involve clearing the pipes, cables and ancillary equipment that has been servicing the tunnel boring machine and preparing for the world record-breaking pipeline installation early next year.”

Hydraulic thrusters will be installed at the Goxhill site on south side of river for the epic pipeline push

The 850-tonne sections of pipe will be pushed on rollers into the new tunnel from Goxhill on the south side. To aid installation the tunnel will be flooded with water.

When one pipe section has been installed, the next will be moved into position, welded to the one in front, and the push will continue until all of the pipeline is installed beneath the river.

When complete it will be the longest hydraulically inserted pipe in the world.