Mackintosh was born in Halifax, West Riding of Yorkshire, the son of John and Violet Mackintosh who had a toffee factory on Queens Road in Halifax, then Albion Mills and also in the United States, Canada, Germany and Australia.

Instead of going to university, he spent a few years in Krefeld in North Rhine-Westphalia, Germany where he ran a Mackintosh toffee factory, and learnt the language.

He was a member of the German international hockey team, prior to the First World War.

In September 1931, he narrowly avoided merging the company with Rowntrees of York.

[1] As a result of a lunchtime meeting at the Savoy Hotel, he bought the A. J. Caley confectionery company in Norwich from Unilever in 1932.

This takeover of Caleys helped the Mackintosh company to expand its range of products notably changing its reliance on toffee to products with chocolate toffee such as Quality Street in 1936 and Rolo.

To launch Quality Street, he had a full-page advertisement on the front of the Daily Mail on 2 May 1936.

He had a large collection of Toby jugs, and had an extensive knowledge of Ralph Wood and Staffordshire pottery.