[3] Osmond Henrys's grandson Peter, a former Special Operations Executive colonel, ran the brewery from 1946 to 1980.

[6] From the 1960s until the early 1990s, Mac's also brewed a range of kids' soft drinks that were sold at their pubs and also in the local ice cream stands and newsagent shops.

[12] In 2002 there was a split between various members of the McMullen family some of whom wanted to turn their holdings into cash whilst others were happy to remain shareholders.

[13] A new independent chairman, Charles Brims, secured a compromise whereby several non-brewing property investments were sold in order to release cash to appease the majority shareholders and a plan was developed to build a new, smaller brewhouse.

[citation needed] As the new Whole Hop Brewery (opened 2006) was more compact than the 1984-built plant, the spare land was sold to Sainsbury's in 2007.

The company owns over 130 freehold pubs, mainly in the Home Counties, with a number in London, including The Spice of Life in Cambridge Circus, The White Swan in Pimlico and The Nag's Head in Covent Garden.

McMullen's is acquisitive and has recently purchased pubs and bars in Cambridge, Chelmsford, Sevenoaks, Fleet, Marlow, Milton Keynes and Bishop's Stortford.

Due to the forced pub closures during the COVID-19 pandemic of 2020–21, Mac's began selling takeaway casks of beer directly from their brewery yard.

[25][26] Hertford Castle is a 5% ABV strong ale brewed with Suffolk barley and undeclared whole leaf hops.

First brewed in 1960, the beer is named after Hertford Castle, where Queen Elizabeth I of England spent much of her childhood.