Image caption Steffan Lewis represented South Wales East in the National Assembly since his election in 2016

The death of Steffan Lewis at the age of 34 brings a tragic end to the promising career of a politician long tipped as a future leader of his party.

In his short time as a Plaid Cymru assembly member he had a big impact on Welsh politics, particularly in the Welsh Government's approach to Brexit.

The father-of-one was diagnosed with terminal cancer in late 2017 but refused to allow his illness to stop his work.

A politician who was well-liked across the assembly, Mr Lewis leaves his wife, Shona, and three-year-old son Celyn.

Image copyright Plaid Cymru Image caption Steffan Lewis with Plaid Cymru colleagues in October 2018

Brought up in Crosskeys and Tredegar, he became Wales' youngest assembly member in 2016 when he was elected to serve the region of South Wales East.

But the fluent-Welsh speaker's journey into politics began at a much younger age.

Born to parents who were both members of Plaid Cymru, Mr Lewis went to a primary school in Swffryd in Blaenau Gwent.

He later moved to the Welsh-medium primary school Ysgol Gymraeg Cwm Gwyddon in Abercarn, and later attended Ysgol Gyfun Gwynllyw in Pontypool.

Young politician

The Islwyn by-election of 1995, triggered when former Labour leader Neil Kinnock stood down as an MP, was when he "really started to get excited by politics and excited by political campaigning".

Image copyright Plaid Cymru Image caption Budding politician: Steffan addressed the 1997 Plaid Cymru conference in Aberystwyth

It was around that time that the young activist went to his first Plaid Cymru branch meeting - and he addressed a party conference in 1997.

The Blaenau Gwent Westminster by-election in 2006 saw Mr Lewis, who is from Blackwood in the Gwent Valleys, stand as a candidate for the first time.

The Celtic football fan came third, but it spurred him on to getting into politics full-time - and a few months later he began working for Plaid Cymru in the assembly.

His work behind the scenes saw him serve as Leanne Wood's speechwriter during her leadership.

Following the retirement of Jocelyn Davies, Mr Lewis was selected to be top of the Plaid Cymru list for his home region of South Wales East - and secured victory in the 2016 election.

Image copyright Steffan Lewis Image caption Steffan Lewis, pictured at around six years old, went to a primary school in Swffryd in Blaenau Gwent

Mr Lewis' mother was a social worker while his late father was a former retail worker, but earlier generations of his family had been coal-miners.

"I'm just the second generation of Lewises not to go underground," he told BBC Wales' James Williams in 2017.

'Made his mark'

Following his election, Mr Lewis made his mark in the assembly as the Brexit spokesman for Plaid Cymru.

He had a major role in the joint Labour-Plaid policy on leaving the EU, published at the beginning of 2017.

Image caption Steffan Lewis's sister Nia (left) organised a charity walk in honour of his 34th birthday

While a row brewed between the Welsh and UK governments over the impact on devolution of Brexit legislation, Mr Lewis called for ministers to protect the assembly's interests by ensuring EU law is preserved in Welsh law.

A senior Labour cabinet minister at the time said that Mr Lewis was the first AM to put the idea on the table.

A Continuity Act was eventually passed as emergency legislation. It never came into force, abolished after ministers on both ends of the M4 reached a deal, but it had been a key part of the government's negotiating strategy.

The act was approved months after Mr Lewis had been diagnosed with bowel cancer following a CT scan in Newport's Royal Gwent Hospital.

Members of the assembly and MPs rallied around the AM - taking part in a charity walk organised by Mr Lewis' sister Nia to raise cash for the Velindre cancer hospital in Cardiff.

'It's okay to be scared'

Mr Lewis spoke emotionally about his experience of living with stage-four bowel cancer in media interviews after his diagnosis.

"I appreciate the fact there are 2,000-odd people in Wales with bowel cancer every year and about 5% of those are younger people, so numerically we are small," he said.

"But still I think we need to talk about the emotional palette that we have when we are going through something as profound and as frightening as cancer.

"It's almost like validating our own emotions and our own feelings - that it's okay to be a young man and to be scared and to allow yourself to explore that, to rationalise it and to talk about it openly."