The former SDLP leader Margaret Ritchie has said she remains "SDLP to the core" even though she has had to quit the party to become a peer.
Ms Ritchie was leader of the SDLP between 2010 and 2011.
She received a non-affiliated peerage in Theresa May's resignation honours list.
The SDLP, which is opposed to members sitting in an unelected chamber, wished the former South Down MP well for the future.
Ms Ritchie explained her decision to accept the peerage to BBC News NI saying she always had been "of the firm belief that you should take seats wherever those seats in chambers present themselves".
She said she realised the SDLP had a policy of not taking seats in the House of Lords, but saw this as "an opportunity to articulate those viewpoints that sadly are missing at the moment".
"We have a party that sits outside the House of Commons being interviewed on the green but not in the chamber doing the work where it counts, and also the DUP who don't represent the 56% of the population [in Northern Ireland] who voted to remain," she said.
"Obviously I had to step aside from the party so as not to present them with a further management difficulty.
"I was quite happy to do that, but I'm SDLP to the core, to my very fingertips, and I will always express those views in a very forthright manner."
Asked why she did not back SDLP members taking seats in the House of Lords when she was party leader she said: "I've been on a journey."
Ms Ritchie, was previously the minister for Social Development at Stormont.
She was elected MP for South Down in May 2010, succeeding Eddie McGrady, but lost her seat in 2017 to Sinn Féin's Chris Hazzard.
Ms Ritchie made history in 2010 when she became the first leader of a nationalist party to wear a remembrance poppy.
She follows in the footsteps of another former SDLP leader Gerry Fitt in taking up a seat in the House of Lords.
He stood down from the leadership of the SDLP in 1979.
In June 1983, Gerry Fitt lost his seat as MP for West Belfast to Sinn Féin's Gerry Adams.
The following month he was made the Baron of Bell's Hill.
There are 37 men and 20 women on former prime minister Theresa May's resignation honours list.
It includes recipients from all four nations of the UK as well as non-political figures and members of civic society.