TERRIBLE news came on Christmas Day that Alice Mahon had sadly passed away.

As the MP for Halifax, Mahon was utterly brilliant, determined, dogged and totally unfazed by the pomp and grandeur of Parliament.

Elected to Parliament in 1987, she was incredibly active on behalf of her constituents and proudly saw herself as a working-class MP.

She had previously worked in the NHS for 10 years as a nursing auxiliary, studied at Bradford University and later taught trade union studies at Bradford College. She had also served as a Labour councillor in Calderdale.

In Parliament she immediately joined the Socialist Campaign Group and was a frequent figure in all campaigns, fighting for workers’ rights on the picket line, anti-racism on the streets and international solidarity around the world.

Mahon opposed the Gulf war in 1991 and later the later Balkans war, bravely visiting Belgrade while it was under Nato bombardment.

In 2001, we travelled together to East Timor to observe the referendum on its future and the end of the brutal war of independence, which cost thousands of lives.

Along with Ann Clwyd MP, we observed all the polling stations we visited very closely. Mahon was fearless even when we saw the effects of military attacks on some of the polling stations first hand.

In 2002, she drafted the first parliamentary motion against British military involvement in Iraq. A supporter of Stop the War, she later told the Labour Party conference: “We were lied to about WMD, and there is no delicate way of putting it.”

She was a great friend to all those who were facing poverty and marginalisation. As a member of the NUPE (later Unison) group in Parliament, she strongly opposed privatisation in the form of PFI schemes and foundation hospitals, which she saw as vehicles for undermining the NHS.

Sadly, Mahon stepped down from Parliament in 2005, became increasingly frustrated with the direction of New Labour, and resigned from the party in 2009.

She came back to Labour when I was elected leader in 2015, and despite suffering macular degeneration and loss of much of her sight, she was a committed and vocal supporter of the anti-austerity socialist agenda we were putting forward.

I have this happy memory of her in the 2017 election campaign at a huge election rally in Hebden Bridge, on the front row beaming with hope and happiness.

Mahon was a great socialist, never a crowd-pleaser or career politician, with an acerbic but human wit, and never afraid to take her case into hostile territory. When she was somehow elected to the Nato parliamentary assembly, she spoke for peace, detente and nuclear disarmament.

Everyone who met Mahon learned much from her about life, principles and determination. I found her a brilliant and loyal friend, on the good days and the bad.

She was one of my best comrades in Parliament and I will miss her terribly. My thoughts go to her family and the people of Halifax she served so well.

Jeremy Corbyn is MP for Islington North. Twitter: @jeremycorbyn.