He volunteered for service with the Royal Navy in 1939 and (in line with his father's business) was assigned to work on motor gun boats.

[1] He secured an entry to the 1948 Grand Prix des Frontières, and practised for the event by driving his Invicta at high speeds on public roads, teaching himself to four-wheel drift around Belgrave Square in London's Mayfair.

The new team found little success, failing even to start the 1952 12 Hours of Reims, but such issues typically did not faze him.

Macklin's social confidence and smooth demeanour made him popular with women, and he would sometimes be more interested in them than racing.

Macklin swerved to avoid hitting the Jaguar of Mike Hawthorn, who was braking hard in a late attempt to pit, and moved into the path of Levegh's car causing it to clip his.

Macklin crashed his Austin-Healey 100S avoiding an accident in which Jim Mayers and William T. Smith were killed.

[5] Macklin joined Facel Vega in Paris, running the export division until the company failed in 1963, when he began working for London car dealership H.R.