Employers need to be flexible to allow staff nursing hangovers to go into work late on Monday or even take the day off if England win Euro 2020, Downing Street said on Thursday.

Boris Johnson’s official spokesman said businesses that could cope with absences should cater for staff who had enjoyed a late night of celebrations.

England kick off in the final against Italy at 8pm on Sunday, with partying likely to go on through the night if they win their first major trophy since 1966.

Asked whether employers needed to be flexible, Mr Johnson’s spokesman said: "We would want businesses who feel able to consider it if they can, but we recognise it will vary depending on the business and company."

On Thursday, some businesses had already begun letting staff know they could arrive late for work, while some primary schools told parents that children arriving late on Monday would not be marked down as "late" in the official attendance register.

The semi-final victory over Denmark on Wednesday night sparked wild celebrations across the country. England had lost their last four semi-finals at major tournaments, stretching back to 1968. 

Victory on Sunday would make Wednesday’s celebrations look like a vicarage tea party.

The Government is also contemplating how to mark the triumph if England are crowned European champions. Officials have discussed a snap Bank Holiday on Monday, although the logistical difficulties of creating an official day off at such short notice make that seem unlikely.

But that did not stop 90,000 fans from signing an online petition calling on the Government to make Monday a national holiday, allowing them to nurse hangovers without going to work. 

The alternative – and most likely – option is a one-off day of celebration, possibly not until the autumn.

Mr Johnson told Sky News that any talk of a Bank Holiday "would be tempting fate", adding: "Let’s see what happens". 

Downing Street said any victory celebrations would be disclosed "in due course", and the Prime Minister’s spokesman said: "I don’t want to pre-empt the outcome of Sunday’s match. Clearly we want England to go all the way and win the final. We will hopefully, when England go on to win, then go on to set out our plans."

Rishi Sunak, the Chancellor, declined to be drawn on the suggestion when it was put to him during a radio interview on Thursday.

A government source said on Thursday night that "various options will be considered" for a bank holiday if England wins. The insider stressed that since the proposal depends on the result of the match, ministers are loath to "get ahead of that".

It is deemed unfeasible for Monday, July 12, the day after the Euros final. On Thursday night there were reports that ministers are considering declaring a bank holiday on July 19 or later in August.

The likelihood is that Downing Street would declare some form of day of celebration to coincide with any victory parade for the players. Any parade would remain illegal under current Covid restrictions, which will not be lifted until July 19. 

But by then many of the squad will be on holiday and the Football Association has privately said that England’s performances would be more likely to be celebrated at a ticketed event at Wembley in September, possibly to coincide with the team’s next international match. The FA has tried to dampen talk of any victory parade.

Downing Street blocked calls for the capacity of Wembley to be lifted from 65,000 to its maximum 90,000 for Sunday’s final.

The stadium is operating at three-quarters capacity under the Government’s Events Research Programme, giving special dispensation and allowing the risk of the spread of Covid at both indoor and outdoor arenas to be evaluated. 

Sources had said increasing the capacity at short notice to accommodate extra fans caused a further public health risk that officials were not prepared to take. 

Mr Johnson would have to sanction any increase in crowd size, and his spokesman said: "There are no plans to extend the capacity."