Developers Elgin Energy want to turn the disused airfield near Kettering - an important base for both the RAF and US Army Air Force during the Second World War - into a home for thousands of ground-mounted solar panels to generate up to 38MW of electricty.
This year marks 60 years since the site, a non-designated heritage site, was last in use as an airfield with the land sold to the Duke of Buccleuch's Boughton Estate.
Kenneth Bannerman, founder of the Airfields of Britain Conservation Trust, said the plan was not a wise move.
He said: "Airfields like these should be preserved and it's a terrible shame that that seems to be the last thing on their [the estate's] mind.
"When you think of all of the incredible effort, bravery and sacrifice, quite frankly it's just a slap in the face.
"Not just to everyone who served there, but also the workers who constructed the airfield who would have been under constant threat for their lives."
Full plans have not yet been submitted to Kettering Council but are expected in the coming months. The site is mainly north and west of the remaining runways with a section on both sides of Brigstock Road slightly further north.
Rachael Gladstone-Brown, estate manager at Boughton Estate, said they had been engaging with nearby residents over the proposal.
She said: "The site is primarily composed of agricultural land and no significant effects are anticipated on the land from the nature of this development.
"A survey has also been conducted and from this valuable feedback, plans were amended to protect the sight lines from the Second World War memorial [south of the solar farm in Geddington Road] and the houses of nearby residents.
"The planning process is in its early stages but all parties will remain in dialogue with the parish council and local residents as the application progresses.”
If approved the solar farm would provide power for thousands of homes and at 68.8 ha would be one of the biggest in Northamptonshire.
Alistair Wildgoose, chairman of Grafton Underwood Parish Council, said he was broadly supportive of the plan.
He said: "My feeling is that the future is more important than the past.
"We should be putting more behind dealing with the issue of green energy."
He added that he felt one airfield preserved in detail would be better than many saved in outline.
Mr Bannerman said he was saddened by the parish council chairman's comments.
He said: "Had it not been for airfields like Grafton Underwood, Great Britain may have lost the Second World War.
"People like those on the local council might not have been free to make a statement like that. Maybe that's something they should think about."
Applicants Elgin Energy already have more than 20 operational sites in the UK with some found in Norfolk, Wales, North Yorkshire and Cornwall.
Another 20 have been approved or are being built in Ireland.
The bid to transform the former RAF Grafton Underwood is not their first plan for a disused airfield. Last year they were granted permission to build a 50MW solar farm on the former Milltown Airfield in Moray. At the time it was the biggest consented solar farm in Scotland.
Elgin Energy declined to comment on the Grafton Underwood plans and instead provided the Northants Telegraph with the Boughton Estate's statement.
RAF Grafton Underwood made headlines earlier this year over fears for the future of a number of crumbling buildings often visited by American tourists.
The under-threat structures were thought to include the main ops room during the war and control tower.
The USAAF 384th Bombardment Group used the base from May 1943 to June 1945 and the 384th Appreciation Society said their main concern was saving the at-risk buildings.
A Boughton Estate spokesman said no decision had been made on the future of the "frail" buildings but that any decision would not be impacted by the "separate" solar farm plan.
The spokesman said: "As planned, we are undertaking a review of each building but our efforts continue to be hampered by acts of anti-social behaviour and vandalism despite security fencing being in place to protect the premises.”
GRAFTON UNDERWOOD DURING THE WAR
Construction on the 500-acre site by George Wimpey and Company began in 1941 and it eventually housed 3,000 US airmen and was officially known as Station 106.
There are several permanent memorials to the 384th Bombardment Group including a stained glass window in the parish church, a red granite memorial stone at the south of the site, a St Christopher statue and chalice in St Edward's RC Church in Kettering and a statue and bell in Kettering Parish Church.
On August 17, 1942, the first Boeing B-17 Flying F Fortress planes set off from Grafton to fly the first mission by these types of heavy bombers from the 8th Airforce. Piloting the lead aircraft was Major Paul Tibbets who would go on to pilot the Enola Gay to Hiroshima in 1945.
Grafton had three runways and two hangars as well as mess halls, a chapel, the 'Foxy' cinema, a barber shop and a tailor.
Still partially standing are the runway control tower and the main ops building as well as many smaller buildings and structures and remains of the runways.