[1] He was born at Fethard-on-Sea in County Wexford, Ireland, the third son of Reverend William Frederick Archdall Ellison,[1] and was home tutored until the age of nine when his father became the director of Armagh Observatory.
Mervyn was entered into the Royal School, Armagh, and during his spare time, he developed an interest in astronomy.
In 1927 he began his undergraduate work at Trinity College Dublin, where he studied physics and was elected a Scholar.
[3] Ellison became senior science master at Sherborne School[4] in Dorset, 1933, then married Patricia Herron in 1934.
With the start of the world war, he organized an Air Cadet Training Corps, then joined the Operational Research Group at the Admiralty.
The following year, he joined the Royal Observatory, Edinburgh, where he continued studies of solar activity, including flares and prominences.