These two banks had already established large regional branch networks and were quickly encroaching upon the London market.

The Surrey, Kent and Sussex Banking Company had been established at Southwark in 1836 and soon had branches in places like Croydon, Brighton, Maidstone and Woolwich.

Continuing rumours about its financial position, and a climate of depreciation in gilt-edged securities, led to a suspension of payments.

The bank itself also directly established offices in Madrid (1917), Barcelona (1917), Antwerp (1919), Brussels (1919), Bilbao (1919) and Valencia (1920).

All the Spanish branches were closed in 1923–24, due to deteriorating economic conditions in Spain and discrimination against foreign banks.

During the economic difficulties of the late 1920s and early 1930s, the bank kept tight centralised control over the continental branch of the business to avoid the dangers of too rapid an expansion in unfamiliar markets, but this policy stunted Westminster's international operations.

The statutory process of integration was completed in 1969 and the new company, National Westminster Bank, opened its doors for business on 1 January 1970.

[13] The Westminster Bank continued to exist as a dormant registered non-trading company until 4 July 2017 when it was dissolved.