MPs will leave the Commons for almost three weeks on Wednesday despite the looming international crisis in Ukraine, provoking warnings Parliament could be "left behind".
At around 7pm, Leader of the Lords Lord Hill will read a message from the Queen, sparking a constitutional procedure involving tricorn hats and Norman French, proroguing Parliament until the State Opening on June 4.
The event will shut down parliament and unlike a normal recess, recalling MPs in the event of an emergency is very difficult and would require a Royal Warrant.
An MP warned parliament's recess could mean Britain gets 'left behind' if the Ukraine crisis develops
Labour MP John Mann said there were many subjects which could be discussed to fill the time - and warned MPs could very well need to be brought back to Westminster to debate Ukraine.
He said: "It's a volatile situation (in Ukraine). We don't want to be left behind.
"I have plenty of Bills which could be debated and voted upon. There are plenty of issues I would like to see discussed.
"A good example would be the Government's drug policy, or its lack of one in my view.
"There is the question of taxation following the Gary Barlow case and why these schemes have been allowed before and why it has gone on for so long."
Foreign Secretary William Hague yesterday warned MPs a recall would be "unprecedented" and could only happen in "extreme circumstances if there is a threat to the United Kingdom".
The break up comes a week before a scheduled recess was due to start on May 22 - the same day as local and European elections - and effectively extends the Whitsun break from six working days to 15.
Speaking in the Commons on Monday, Tory MP Andrew Bridgen challenged William Hague on the mechanics of bringing MPs back, when the Foreign Secretary made a statement on Ukraine.
Hague replied: "It is no simple matter for the House to sit during prorogation, which is one of the reasons for making my statement. Indeed, it would be unprecedented.
"Nevertheless, the Civil Contingencies Act 2004 provides a means for the House to sit in extreme circumstances, if there is a threat to the United Kingdom.
"The Leader of the House (Andrew Lansley) will be much more familiar with the details than I am, but I think you should bear in mind that the threshold for the assembly of Parliament during prorogation is very, very high."
Speaking on Monday, Lansley rejected claims the government had run out of steam - and said it was Labour who had insisted on delaying the Queen's Speech until after the elections on May 22.
He told the Radio 4 World at One programme: "Not at all. We've got 20 Government Bills and five private member's Bills that are likely to have secured approval.
"We've sat in the last 12 months, by my calculation, 155 sitting days, which is actually in line with previous years and is slightly more than in many previous years.
"It's always the case, every year, that once we've completed the business that has been set down for a particular session, once the government bills and other bills have completed their passage, then Parliament rises."