It expanded steadily as a regional society until the late 1950s when it began a major expansion drive, partly through branch openings but also some 55 acquisitions.

Following the acquisition of the Bristol & West in 2005, the Britannia became the second-largest building society in the UK (based on total assets of £36.8 billion) at 31 December 2007.

By this time the society had around 1,750 members; this was to increase to 4,600 (now shareholders) by the end of Thomas Shaw’s long tenure.

[7] Four years after the death of Arthur Shaw, the directors decided to look outside the Society for fresh leadership.

In 1933, the 29-year-old [Sir] Hubert Newton was recruited as Secretary; he became a director in 1938 and under various titles, ran the society until he retired as Chairman in 1985, a span of 52 years.

Newton’s involvement with the association (he was later chairman of the BSA) gave him a range of contacts which facilitated the Leek's post-war acquisitions.

Redden’s history recorded that in 1935 less than 2,000 out of 30,000 members were local and branches had been opened as far afield as Manchester, Liverpool and Bristol.

[7] Led by Hubert Newton, the Leek & Moorlands embarked on a sustained strategy of both branch openings and the acquisition of smaller building societies.

The long serving managing director stood down in 1984 and Sir Hubert Newton retired as chairman in 1985.

[8] The last acquisition was the deposit base and branch network of former building society Bristol & West (bringing with it approximately 700,000 customers) from Bank of Ireland in May 2005.

This was the first major re-mutualisation in the United Kingdom (following the earlier demutualisation trend) and brought membership of the enlarged society to just under three million.

[13][14] On 29 April 2009, Britannia members voted overwhelmingly to become part of Co-operative Financial Services, the first such merger between different types of mutual under the Butterfill Act.

Britannia was official sponsor of Stoke City F.C., which played in the Premier League between 2008 and 2018, and lent its name to the club's stadium.