Richard III Society declares peace over Bosworth track plans
The Richard III Society has said it now wants to work with a firm planning to build on the Bosworth battlefield.
It was among various groups opposed to plans for a driverless car test track on part of the site in Leicestershire, where King Richard was killed in 1485.
However, the scheme was approved and now the group says it will back a survey to create a 3D map of the land "how Richard would have seen it".
But the Battlefield Trust said it was concerned about a precedent being set.
Hinckley and Bosworth Council approved the plans in September despite opposition from the Richard III Society, Battlefields Trust and Historic England, along with a 15,000-signature petition.
About 27 acres - around 1% of the battlefield site - is to be built on.
Japanese tech company Horiba Mira said the facility for driverless cars near Higham-on-the-Hill would create about 1,000 jobs.
Sally Henshaw, secretary of the Richard III Society, said it was "very sad" the plans had been approved but they had to "look forward".
"Soon after the decision we discovered there was no third party right of appeal and the only way to challenge it was if there was some legal irregularity, which there doesn't seem to have been.
"The [new digital map] will show the battlefield as it is now and then be able to go back to 1485 before the hedges and fences were there and give you an idea of how Henry and Richard would have seen it," she said.
The Battlefields Trust said it "remains disappointed" the plans were approved.
A Horiba Mira spokesman could not give details of the project for either the map or track development but said it expected to work with a "variety of stakeholders on the archaeological aspects of the site" as the scheme progressed.
The Battle of Bosworth took place on 22 August 1485, and saw Henry Tudor defeat and kill Richard III, whose remains were eventually found beneath a Leicester car park in 2012.