In the first part of the twentieth century, Highgate Brewery acquired other breweries, and transferred their business to Sandymount Road.
In 1914 Agnes Mountfield became Highfield’s head brewer. She is believed to have been the first female head brewer in the country.
In 1924 James A. Fletcher and John Lord formed Walsall Breweries Proprietory Limited to take over the business of Arthur Beebee Limited, based at Malt Shovel Brewery, 130 Sandwell Street, Walsall, and its eleven public houses.
The business continued to grow. By 1939 the brewery owned over fifty public houses, produced 50,000 barrels of beer per year, and employed sixty five staff. Around that time the brewery entered negotiations with Mitchells & Butlers of Cape Hill, Smethwick, who were interested in purchasing the business. On 22nd July, 1939 when negotiations had been completed, Mitchells and Butlers purchased the whole concern, including Highgate Brewery, Walsall Breweries Proprietory Limited, and all of the company’s public houses.
Initially Mitchells and Butlers had decided to end production at Walsall, which was their usual practice for any brewery they acquired. The intention was to turn it into a depot, but World War 2 intervened. At the onset of war, every brewery received an allowance for malt and hops, which were rationed. In order to draw the ration, and to satisfy the great demand for Highgate dark mild ale, Mitchells and Butlers took the unprecedented decision to continue brewing at Highgate.
After the take-over, the bottling plant closed, and the product range was limited to Mild Ale, and Old Ale (produced between September and February, and bottled at Cape Hill), the last bitter being produced in 1940. During the war the Auxiliary Fire Service was stationed at the brewery, and company’s mild ale continued to be extremely popular.
The next major change took place after 1960 when William Butler & Company Limited of Springfield Brewery, Wolverhampton became part of Mitchells & Butlers.
The distribution side of the business at Walsall was transferred to Springfield Brewery, and the production of Highgate Old Ale ceased.
Mitchells & Butlers replaced it with Butler’s Old Ale, brewed at Springfield.
In 1961 Mitchells & Butlers merged with Bass, Ratcliff & Gretton to form Bass, Mitchells & Butlers Limited.
By the early 1980s, lighter bitter ales, and lager had become more fashionable, but Highgate still managed to produce around 100,000 barrels of mild each year, with about thirty staff. In 1982 the number of staff was reduced to twenty two, and further reduced in 1985 to twelve. It became Bass, Mitchells & Butlers Limited’s smallest brewery.