[1] He then joined his father in a joint legal practice in 1933 under the firm name JJ & Denis McGrath.

[6] He supported the agenda of urban renewal in the city proposed by councillor George Porter.

Porter and councillor Gerald O'Brien visited McGrath's home after a council meeting to ensure his support, thinking it essential for the renewal to occur.

"[7] He was involved in a public selection controversy in 1965, where first-term councillor Matt Benney as chosen as the Citizens' nominee for the mayoralty by the association's executive, but Benney withdrew his nomination after it became evident that the majority of sitting Citizens' councillors instead favoured McGrath.

The first was in 1970 over industrial issues affecting Air New Zealand, the second in 1972 regarding equal pay for women, and the third in 1973 over a review of parliamentary salaries policy.

[13] McGrath was appointed a Commander of the Order of the British Empire in the 1972 Queen's Birthday Honours, for very valuable services to the community.