Ruth Davidson has claimed she was “genuinely astonished” that Boris Johnson did not block her peerage.

The former Scottish Tory leader, who stepped down as an MSP in May, will formally join the House of Lords on Tuesday and has been a persistent critic of the Prime Minister.

She will be known as Baroness Davidson of Lundin Links, a reference to the Fife village where she grew up, and has vowed to continue to speak out against the UK Government when required.

She recently described cuts to UK overseas aid as a “bloody disgrace” and has criticised the Prime Minister’s plan to introduce a requirement for voters to present ID at polling stations. Ms Davidson, a remainer, has also clashed with Mr Johnson over Brexit.

Speaking about her peerage to the Scottish Mail on Sunday, she revealed Mr Johnson had not personally proposed it but added: “I’m astonished he signed it off. Genuinely astonished. When it came through, I was like, ‘Are you f******* kidding me?’”

Ms Davidson has called for reform to the Upper House to make it more democratic and has not ruled out a return to frontline politics in future.

However, her comments will further dampen speculation that she could be handed a ministerial post in Mr Johnson’s government. She has said she will not take on any “big jobs” until her two-year-old son is in school.

She added: “Do you know what’s great about the House of Lords? Part of the oath that you sign up to is that you have to be independent minded.

“You can tell your whips to naff off if required. That suits me just fine. I don’t think I’ve ever been accused of being lobby fodder, and I’m not going to be.

“I do sometimes think my government is wrong, and I’m going to say it.”

The 42-year-old will be introduced at the Lords tomorrow by two former Scottish Conservative colleagues – former director Lord Mark McInnes, and former party chairman and former Advocate General Lord Keen.

The SNP said Ms Davidson had “now fully sold out” by entering the House of Lords despite being “the leader responsible for a Scottish Tory operation to keep Boris Johnson out of Downing Street.”

A party spokesman said: “It’s questionable whether the good Fifers of Lundin Links will appreciate being associated with such an insult to democracy as the unelected Lords.”