Terrorism is Peter Taylor’s patch, and as a veteran BBC journalist, he’s talked to a few.

Talking at Corpus Christi College last night, at the invitation of the British Red Cross, Taylor saw some elements of commonality in Northern Ireland, Al Qaeda and Islamic State (IS). Born out of discrimination, repression and exclusion, each shares a vision which attracts recruits, financial aid and fear.

Use of violence to achieve a political outcome has a long history; it has met with success all over the world. Accepting violence as a means to an end has catapulted erstwhile ‘terrorists’ into democratically elected leadership: Kenyatta in Kenya, Begin in Israel, Arafat in the West Bank, Mandela in South Africa and McGuinness in Northern Ireland. Their key roles in – respectively - the Mau Mau rebellion, the bombing of King David Hotel in Jerusalem in 1946, the Palestinian Liberation Organisation (PLO) and the Munich massacre in 1972, the African National Congress (ANC) and the Irish Republican Army (IRA) preceded their subsequent government positions.

Taylor suggested that the IRA’s aims were predominantly secular: territory and equality rather than bolstering the Roman Catholic faith. Al Qaeda and IS share a commitment to an Islamic Caliphate, but only IS have attempted to establish one under Sharia law, rather than drive the infidel (Western armies) from Islamic lands. Both use selective interpretations of the Koran to justify their violent acts.

According to Taylor, Western intervention is directly responsible for the rise of IS, which came to power in the chaos of the post-Iraq war of 2003. Excluded from government, repeatedly let down by Sh’ia politicians, and having disaffected and dispossessed - but experienced - Iraqi Army officers in its ranks, IS’s ruthless reputation has preceded its territorial gains.

‘IS has adopted the terror techniques of Genghis Khan: killing every last cat and dog and raising a village to the ground,’ Taylor said. Funded from oil, looting and extortion, its attraction for British-born Muslim youth is a source of serious concern.

Yet ultimately, Taylor believes, IS will ‘ fall victim to its own savagery – a savagery that repels the majority of Muslims whose support it needs to survive’. There is only so much violence we will accept, and the tipping point will come.

Taylor’s personal courage, his integrity, his good humour and humanity were much in evidence. His encounters with terrorists were also encounters with men and women - the same as all of us until raised to revolt.