W hen thinking and writing about Liam Clarke two words come to mind "fearless" and "formidable".

Liam faced his illness, a rare form of cancer, with the same bravery that marked his journalism. His ability to hold on for so long after the terminal diagnosis also demonstrated his formidable personal strength.

Even a week ago, just before his death at the weekend, Liam was still scooping the rest of us when it came to political stories. He got ahead of the pack for the 'Belfast Telegraph' with the first interview with First Minister-in-waiting Arlene Foster shortly after she was elected unopposed to lead the Democratic Unionists. This was yet another example (we didn't know it would be his last) of Liam getting his story out first before the opposition.

It is also supremely ironic that the man at the centre of one of his Liam's greatest ever scoops - the unmasking of south Armagh smuggler and IRA commander Thomas 'Slab' Murphy - is currently awaiting his fate after being found guilty just before Christmas of tax evasion.

In the Special Criminal Court, Murphy cut a lone, isolated figure as he was found guilty of failing to pay his taxes in the Republic. Back in 1988 no one could ever have imagined 'Slab' and his power being challenged through the courts of the land.

In that time he held sway over the IRA's South Armagh Brigade and helped through his organisational resources to smuggle tonnes of Colonel Gaddafi's weapons into Ireland. And in the mini 'Republic of Fear' along the border there was a vow of murderous silence that ensured the likes of Murphy would never be exposed.

That was until Liam Clarke and the 'Sunday Times' investigation team decided to probe the vast wealth of the South Armagh farmer and the allegations that he had been IRA Chief of Staff.

Murphy sued for libel in 1988 but the paper and Liam held firm, eventually winning the case after several years, and exposing 'Slab's' role in the Provisionals' war. For this, Liam became for a time a marked man and his journalist colleagues know of at least one IRA plot to kill him in the late 80s.

Yet Liam's compassion for people regardless of their politics stretched all the way from the fringes of Ulster loyalism to Sinn Féin and IRA members. I know for a fact that Liam found out about a plot to kill a senior Belfast Sinn Féin member by loyalists in the early 1990s. Liam immediately contacted the Sinn Féin activist and warned him about the attack advising him to change his routine and beef up his security.

The warning was heeded and, mercifully, the attack never took place.

His willingness to help a member of a movement that included others willing to kill Liam at one time was a measure of the man. It was also part of his political philosophy. He regarded 'armed struggle' and political violence as not only immoral but also futile and counter-productive. This is probably why the young radical left-wing student from a Protestant background in the north west joined the post-ceasefire Official Sinn Féin/Republican Clubs, later to become The Workers Party in the 70s.

By 1980, Liam was co-editor of the WP paper 'The Northern People' and worked alongside future 'Fortnight' editor Robin Wilson. They were a formidable duo who turned the paper away from being a dull, ideological leftist tract into an often interesting left-leaning weekly tabloid that even broke some news stories including, for instance, a scoop about a new plastic baton round weapon the RUC was about to deploy.

However, Liam had ambitions to get into mainstream journalism away from a party-line paper. While he continued to sympathise with the WP line on Northern Ireland, Liam realised that journalism and political activism shouldn't really mix. When you sign up to work on a mainstream paper or broadcaster you hand in your party card. So he struck out in the local media first and quite successfully with 'The Sunday News', the paper for which I also worked as Dublin correspondent in the early 1990s.

He joined 'The Sunday Times' in 1984 and became a highly regarded member staff. Its pioneering editor in the 80s, Andrew Neil, was highly supportive and admiring of Liam's work.

While arguably Liam's greatest scoop was the exposure of Slab Murphy, who now faces a prison term for not paying his taxes, there were other huge stories that he worked on. He was among the first journalists to suggest there was a super-spy at the very heart of the IRA's counter-intelligence/informer-hunter unit known as 'Stakeknife'.

He could be amusing too with his anecdotes, especially the one he told about being chased with a wheel brace by Sean McStiofian, the former Provo chief of staff. Liam had turned up on his doorstep with a list of questions about his career.

In the craft of writing, his prose was seamless, particularly in his columns and the books he wrote. He penned one of the best books about the 1981 hunger strike and its role in the rise of Sinn Fein. His 'Broadening The Battlefield' remains one of the most important works from the 80s for anyone studying the trajectory of the Provisional movement from out of the cul-de-sac of armed struggle into normal democratic politics.

When I worked with him on the ST between 1996 and 1997, he broke a number of important stories about the Drumcree crisis and the IRA ceasefires.

He encouraged me to sniff out a few scoops of my own including an LVF plan to foment sectarian strife in east Belfast by burning a Protestant church and then spreading lies that Catholics from the Short Strand were behind it.

Liam was generous with his contacts and his advice often given out over a sensational bottle of red wine in Nick's Warehouse or upstairs in the Morning Star, the latter a particular favourite meeting place for us and our contacts at the time.

And when I had to have surgery to have a tumour excised from my inner thigh in that year Liam was incredibly supportive as I took time out to recover from the operation.

Being a fearless reporter, Liam saw no difference between standing up to tell the truth about Slab Murphy or challenging the power of the British state.

He and his equally formidable wife Kathryn were arrested after they published MI5 and police covert transcripts of conversations between Dr Mo Mowlam and Martin McGuinness.

In 2003 police officers raided the Clarke family home and arrested both Liam and Kathryn over an alleged breach of the Official Secrets Act. They were taken to Castlereagh Holding Centre and questioned for almost a day about the transcripts.

The material Liam and Kathryn obtained (yet another classic Liam scoop) exposed a chumminess between Dr Mowlam and Martin McGuinness.

The transcripts were later used in the second edition of the couple's biography on Martin McGuinness, 'From Guns to Government'.

Typical of both formidable characters, Liam and Kathryn sued the PSNI for wrongful arrest and won. By taking their legal action, Liam and Kathryn bolstered the cause of free journalism unfettered by political constraints or state control.

When he retired after his long stint as Ireland Editor of the 'Sunday Times', Liam went back to local journalism and became Political Editor of the 'Belfast Telegraph'.

Energy

He seemed to be enjoying a late boost of energy and refreshed interest in local politics.

Liam was there for all the big set-piece events that have led to the current power sharing arrangement at Stormont.

I recall walking with him along a beach at St Andrews in 2006 as our conversation oscillated between talk of our respective families and his predictions, ahead of the deal, that Ian Paisley would soon sit down in government with Martin McGuinness.

Through his network of contacts, Liam was certain of this positive assessment of where the talks were going even while the press and media were locked out of the negotiations.

He remained a man of the broad, sensible left and was a trade unionist to the end.

Irish NUJ secretary Seamus Dooley said: "Liam was a fearless journalist. He was never afraid to challenge authority and was always prepared to stand up for the principle of media freedom. In 'The Sunday Times', and more recently, in the 'Belfast Telegraph' he covered some of the most significant events in the history of Northern Ireland.

"As a columnist he was insightful, authoritative and, at times, provocative. He commanded respect across the political divide and his death is a loss to journalism in Northern Ireland."

There is that word again - 'fearless' which combined with a formidable intelligence, knowledge and writing style best sums up the life and career of Liam Clarke.

Henry McDonald is Ireland correspondent for 'The Guardian' and 'Observer'