Former Scottish Labour leader Anas Sarwar dons red robes and ermine to take seat in the Lords

Wearing the traditional scarlet robes with white ermine collar for the ceremony in the upper chamber he was supported by two former Scottish Labour MPs, Baroness Liddell of Coatdyke and Lord Robertson of Port Ellen, as he swore allegiance to the King.

The 43-year-old was greeted with a handshake from the Leader of the Lords, Baroness Smith of Basildon, as he left the chamber.

Lord Sarwar had been re-elected as an MSP for Glasgow in May in the Scottish Parliament elections, but he led his party to its worst result in the history of devolution, being reduced to just 17 MSPs in Holyrood.

Ahead of the campaign he made the decision to call for Sir Keir Starmer to quit as Prime Minister, but received no backing from any other senior Labour figures at that time.

He then announced he was quitting as an MSP during the parliament's summer recess, triggering a leadership election, and anger within party ranks.

As a regional list MSP, rather than a constituency MSP, his going did not force a by-election, and his place was filled earlier this week by Scottish Labour's Monica Lennon. She had hoped to be on the ballot in the leadership election, which is due to end in a fortnight.

However she failed to gain enough parliamentary support, and the choice for members is between MSPs Michael Marra and Joe Fagan.

Making his maiden speech in a later debate, Lord Sarwar, who is now a trade minister in Andy Burnham's government, thanked his family and the “great people of Glasgow” for getting him where he is. His family, including his father Mohammed Sarwar, who was the UK’s first Muslim MP, watched from the gallery.

Lord Sarwar said: “I played my part in helping the Labour Party succeed at the last general election, but our new Prime Minister must succeed, this Government must succeed, and most importantly of all, our country must succeed. I am determined to play my part in making that happen.

“There is also, in my view, a bigger fight that I can’t walk away from, and I’m determined to play my part in.

“That’s what I believe is the fight for the heart and soul of our nation – it’s about who we are as a people and who we are as a country, and for me, it actually goes beyond the usual mainstream political divide.

“And that is: who are we as a country? Do we continue to look out for and love our neighbour, or do we treat them with suspicion?

“Are we a country that succumbs to the politics of division and hate, or are we going to make sure that we have a country and a politics that believes in unity and hope?”

He also said there had been successes in the first two years of the Labour government, but the party had not lived up to voters’ expectations, and he remains “heart-sore” at the outcome of the Scottish election this year.

Addressing his previous calls for the House of Lords to be abolished, he said he did so “questioning the principle, not the purpose or the people”, and he continues to support a “more democratic and more representative upper chamber”.

Following Sir Keir’s departure, Lord Sarwar was made a peer shortly after Andy Burnham entered No 10.

Scotland's First Minister John Swinney previously accused Lord Sarwar of “hypocrisy” and an “appalling level of judgment” for taking the peerage.

“He said before the (Holyrood) election he had absolutely no interest in going to the House of Lords, he only wanted to be First Minister of Scotland.

“Then, after the election, Anas Sarwar has accepted a place in the House of Lords – a body, by the way, he wants to abolish.”