Actor Hugh Bonneville and comedian John Bishop were blown away after discovering their ancestors worked four doors apart in Dublin and were believed to have marched together in support of workers’ rights.

DNA Journey, which returns on Tuesday for a fourth series on ITV, will see four celebrity pairings unearth their past and make life-changing discoveries in South Africa, Ireland and Norwich and St Helens, in England.

The first episode will see Bonneville and Bishop, who became friends after a chance encounter in a Covid vaccination centre, cement their friendship with a trip to discover their family history.

Veteran actor Bonneville, who is best known for playing the Earl of Grantham in the Downton Abbey films and TV series, continues the research of his family tree following the death of his brother.

John Bishop about Ireland show
Comedian John Bishop, who (Ian West/PA)

The 59-year-old looks to discover the truth behind his family name and his middle name Bonniwell – which later transformed into his stage name Bonneville.

He also finds his three times removed great-grandfather who worked at London’s Somerset House and dedicated his life to improving working conditions for sailors, before building a school in Wales.

Bonneville connects with his cousin before it is revealed he has a strong connection to Dublin and that his ancestor was a journeyman baker.

The actor is paired with Liverpool-born comedian Bishop, who says he has always felt a deep affinity with his Irish roots but knows little about them.

The 56-year-old discovers an ancestor, who made the journey from Ireland to Liverpool, and, despite a few brushes with the law, built a business in the booming salt industry.

He also travels to Dublin, where he uncovers a three times removed great-grandfather who is a skilled musical instrument maker and trade unionist, who fought for better rights on behalf of his whole profession.

It is later discovered that Bishop’s ancestor at one point worked four doors apart from Bonneville’s relative and as trade union men it is believed they both marched together through the streets of Dublin in support of worker’s rights.

DNA Journey starts on Tuesday March 7 on ITV and ITVX at 9pm.