Sinn Féin's mystery donor who provided the party with a £1.5m donation was an 82-year-old former motor mechanic and driver, William E Hampton, who died in Pembrokeshire, Wales last year.

Belfast-based O'Muirigh Solicitors, who handled much of the legal brief for Sinn Féin, told RTÉ News that in a will made "in the 90's", Mr Hampton left amounts to a number of individuals and stated that 'all the rest is residue' be given to the party.

Northern Ireland Electoral Commission data indicates that in April and May of this year Sinn Féin received a total of £1.5m, arising from the Hampton will.

It is understood that further amounts may be received when the legal work is completed but that the substantial portion of the money due to Sinn Féin has been allocated.

A spokesperson for O'Muirigh Solicitors described William Hampton as a long-term supporter of Sinn Féin.

He was born in London in December 1935 and held a British passport.

He may have lived in Ireland for a time and "several years ago, he made it known that he would be making a contribution to Sinn Féin in his will."

The £1.5m donation received by the party is thought to be the largest amount received from an individual by any party in Northern Ireland.

Sinn Féin's annual accounts related to the party in the Republic of Ireland detail how the party received donations of €127,957 in 2017 and €99,577 in 2016.

As a result of the £1.5m received by the party in Northern Ireland during the February and March this year, the party's total of public funds and private donations £1,591,616 was five times greater than the combined total of seven rival parties.