He was the son of Robert MacDonnell and Virginia Mary MacDonnell.
In 1901 the family are living in house 11, De Burgh Terrace, Londonderry. Robert is recorded as being a Bank Official.
By 1911 they have moved to house 30, Mill Street, Ballymena. The father is now a Bank Manager.
His wife is Anne Louise MacDonnell (wife) of The Square, Portaferry (also later of Belfast Bank House, Whitehead).
Around that time, MacDonnell volunteered and enlisted as a Gunner with the Royal Garrison Artillery.
He died on 18th April 1970.