The confusion follows a bust-up between unions and employers on the industry’s largest working rule agreement covering more than 500,000 workers, primarily in civil engineering and the ‘biblical’ trades.

Contractor representatives on the Construction Industry Joint Council have rejected union calls to agree one extra day’s paid public holiday, in order to allow workers to pay their respects to the Queen.

In a statement, the employers’ side said: “Taking all relevant factors that apply into account, it will be for each business/employer to determine how they will view the day, and whether time off, paid or unpaid, will be given.”

The decision not to honour the bank holiday marks a significant departure for the CIJC and is at odds with the other main construction industry agreements.

Previously it has recognised all additional bank holidays, but the CIJC has this time blamed a lack of warning about the date of the Queen’s funeral for its decision.

The NAECI ‘blue book’ agreement covering major project mechanical engineering and both parts of the Joint Industry Board agreement for electricians and plumbing have agreed to honour the additional paid public holiday.

Unite general secretary Sharon Graham said: “Following pressure from Unite, workers on major construction projects such as Hinkley Point and the Silvertown tunnel are being paid for the bank holiday for the Queen’s funeral.

“These employers have taken the correct decision. It is to say the least inexcusable that the CIJC has not followed suit.”

Unite said it has already received an email from a major joint venture company on HS2 indicating that they do not require their contractors to pay workers holiday pay on the day of the Queens funeral unless additional bank holidays, such as the Jubilee, are covered in their agreements.

Earlier this week the Construction Leadership Council told firms in guidance that there was no obligation on them to suspend business during the funeral of Queen Elizabeth II, as per government guidance.

Although major contractors like Sir Robert McAlpine, Wates and Laing O’Rourke have announced they will close offices and sites for the day.

Unite national officer for construction Jerry Swain said: “The construction trade federations and their members should be hanging their collective heads in shame.

“The federations now need to take a long hard look at who they have representing them.

“It is clear they need to appoint representatives who have a grasp of what is taking place rather than simply sending messengers. Who have failed the industry and the nation.”