Fr. Mercer was already known as a builder; he had established the new parish at Cranford.
To his time date:the Lourdes Grotto in Peter Avenue, the enlargement of the Clergy House, to provide a room for meetings, the reconstruction of the Sanctuary (already planned by Fr. Eldridge) to meet the requirements of Vatican II, and the embellishment of the Lady Chapel.
The works included: the erection of the present mosaic-faced altar, obtained from Italy; the demolition of the pulpit and most of the altar rails; and the conversion of the Baptistery into a Repository.
This last change entailed adopting temporary arrangements for Baptism.
The Altar was consecrated by Cardinal Basil Hume on 17th May 1979.
The founding of a Handicapped group (now very active) took place at an Inaugural Mass said by Bishop Philip Harvey in January 1978.