There is no known precedent in professional English football for the offence, although Chesterfield were docked nine points in 2001 for financial irregularities, including falsifying gate receipts and giving a player two contracts.

Only two Premier League clubs have ever been docked points, with Middlesbrough losing three in 1996-97 for the unauthorised postponement of a fixture and Portsmouth nine in 2009-10 for going into administration. Both were subsequently relegated.

Watford, who have made their best-ever start to a Premier League season after taking 12 points from their opening nine games, have refused to deny filing the falsified letter, although it is understood club officials insist they would have done so unwittingly.

The Telegraph has learnt an internal inquiry is being conducted – and an independent legal firm has been recruited to examine documents – ahead of a deadline of next week for Watford to respond to the EFL. A club spokesman said: “There are two ongoing investigations. It would be inappropriate to comment further until those investigations reach completion.”

It is understood Watford’s probe has not uncovered any other financial irregularities, although the EFL is certain to check its own records to ensure nothing else was amiss with the club’s filings.