By Trevor Timpson
The Euston arch once stood at the head of a spacious square
Those who want to see the Euston arch rise again are adamant that it must be on the same scale as it was originally.
A half-size model in the concourse of the new Euston station, for instance, will not satisfy them.
They believe the arch should be rebuilt in the same material. And they think it should be on the station site, not somewhere else.
But compromises will have to be made, they admit.
First, in the arch's position. If it were rebuilt on its original site it would be some way down platforms eight and nine of the present station.
Even before it was demolished it had been engulfed by the spread of Euston, with the station hotel blocking the view of it from the Euston Road.
And the redeveloped station could spread even further south than the existing one, with talk of 400-metre long platforms like those for the Eurostar at St Pancras
Then, there is the method of construction. The arch - designed by Philip Hardwick and completed in 1838 - might have looked like an ancient temple, but it was built to an inspired design using the materials of the time.
A brick, wrought iron and timber core was encased in stone.
Engineer Alan Baxter, on behalf of the Euston Arch Trust, proposes a steel frame and a stone outer shell, leaving enough space for stairways, lifts and service ducts leading to the space in the pediment above, and a basement - possibly a nightclub - linking the arch with the existing stone lodges on either side.
Choosing materials will also be complicated. The Trust has said 60% of the original stone may be in the Prescott Channel in east London. But it is not certain how much of it can be used. Many pieces were badly damaged during demolition.
For instance, the piece hoisted from the channel in 1994 - an operation seen on the BBC show One Foot in the Past - is in very good condition, says presenter Dan Cruickshank, but the bottom third of it is missing.
"The re-using of old stones is terrific," says Mr Cruickshank, "but it carries a huge burden of complexity and cost."
There is plenty of Bramley Fall stone available at Blackhill, says Kevin Mone
"Some of the trustees don't see it as a problem to entirely use new stone. I do," he adds.
He is keen to portray a reconstructed arch not as a "pastiche", but as a "major heroic repair" like the Frauenkirche in Dresden, the church which was rebuilt after it was ruined by allied bombing in World War II.
Alan Baxter says any stonework from the Prescott Channel which can be re-used will be enough to give authenticity. "There might be 10% original stone, 90% new."
Where will the new stone come from? The site of the Bramley Fall quarry, which provided the stone for Hardwick's arch, is now wooded parkland above the River Aire in the western suburbs of Leeds.
Similar millstone grit is still produced in quarries north and west of the city.
Blackhill quarry at Bramhope north of Leeds is one which, the Euston Arch Trust hopes, could provide stone for the reconstruction. Manager Kevin Mone says the stone produced there has been sold as Bramley Fall stone as long as his family has worked the quarry.
"There's plenty of stone down there" says Kevin Mone. It is on the same vein of rock as Bramley Fall itself, he says, and has been used recently for restoring the ancient Kirkstall Abbey.
The Euston Arch weighed over 4,000 tonnes - but Blackhill quarry carries out several blasts a year, one of which will typically bring down 8,000 tonnes of stone.
Part of the arch (inset) was lifted from the Prescott Channel in 1994
The stone in the Prescott Channel is under the de facto guardianship of British Waterways (BW) - just at the spot where it is building a new lock to enable the route to be used for Olympic construction traffic.
"Removal of the stone would be both costly and would also affect the schedule of planned works on site," says BW.
It says it is keen to balance the need for the development of the site to provide transport routes into the Olympic Park, with the requirement to protect and conserve historic sites.
"By ensuring the stones are well-managed in their current underwater position British Waterways is ensuring that the stones may still, perhaps when the Trust or another donor can raise the funds, be able to be removed in part or full, in the future," BW adds.