The Tories and Liberal Democrats are giving up a £520,000 bequest from a former nurse amid confusion over whether she actually intended the money to go to the public purse.
The coalition parties moved to quell a wave of criticism after it emerged that Joan Edwards's will left the money to "whichever government is in office at the date of my death".
Officials insisted they had acted in good faith and stressed the executors, solicitors Davis Wood, had taken the decisions and merely notified them that they were beneficiaries of the estate.
In a further twist, the law firm insisted they had specifically checked with Miss Edwards, who died last September aged 90, what she wanted to happen.
"The will was drafted by a solicitor at Davis Wood in 2001," a statement said.
"At the time of the instructions received from the late Miss Edwards, the solicitor specifically checked with Miss Edwards about the unusual nature of her proposed bequest and it was confirmed by Miss Edwards at the time of her instruction that her estate was to be left to whichever political party formed the government at the date of her death."