Sales of Scotland’s beloved fizzy drink increased 60% in the year after the nationalists upped their number of seats from six to 56 to become the third biggest party in Westminster.
Bars, cafes and vending machines across the parliamentary estate dished out 8,708 cans or bottles in the financial year 2015-16 - up from 5,452 the year before.
And it is more than double the 4,285 bottles and cans of Irn-Bru bought in 2012-13, according to figures released to the Press Association under the Freedom of Information Act.
Thirsty MPs, their aides and other parliamentary staff are on course to drink another 8,493 cans or bottles by the end of the financial year next April.
Patrick Grady, SNP MP for Glasgow North, said the fizzy drink gave politicians “sustenance” through the long days in the Commons, which often sits into the evening.
He said: “Barrs, which produces Irn-Bru, is an independently owned company which plays an important role in the economy of central Scotland and the country as a whole.
“Famously Scotland is the only country where Coca-Cola is not the biggest selling soft drink.
“But it looks like we’re making progress in the House of Commons and perhaps the taste will catch on among MPs and staff from south of the border.”