To mark the day, staff at the branch in Plymouth Road donned traditional period costumes to serve up a celebration cake for their customers.
The branch first opened in May 1911 as an office of the National Provincial Bank of England. This bank had been founded in 1833 and by the end of 1910 it had around 350 branch offices, including over 90 in Wales. The bank was rapidly expanding its branch network and actively seeking new locations in which to trade. In 1909, the manager of the bank's Cardiff branch had suggested to the company's directors that a sub-branch should be opened in Penarth.
During the late 19th century, Penarth had been transformed from a small village of just over 100 residents in 1851, to a town of over 14,200 people by 1901. This extraordinary growth partly resulted from the construction of Penarth docks to transport coal from the South Wales coalfield, and also from the arrival of the railway which stimulated the town's development as a popular seaside resort. The town became known as 'the Garden by the Sea'. Given this spectacular growth, the bank's directors immediately approved the opening of an office in the town.
In September 1909 the bank identified a building in Plymouth Road and the following year work began on adapting the leased premises for banking use. While this work was underway, the bank rented a lock-up shop at 9a Royal Buildings, at the junction of Victoria Road and Stanwell Road, which is where the branch opened for business on 22 May 1911. Its first manager was E J August, from the bank's Cardiff branch.
The branch was one of nine new Welsh offices the bank intended to establish in that year. In 1912 the business moved to the newly-completed Plymouth Road premises, which included residential accommodation on the upper floors for the branch manager.
By the early decades of the 20th century, banks faced increasing competition and were forced to grow in order to compete. In 1918 National Provincial Bank of England merged with Union of London & Smiths Bank, which had over 230 branches. The new bank traded through more than 700 local offices and in 1924, following a series of acquisitions, the bank's name was shortened to National Provincial Bank. By this time the company was one of the emerging 'Big Five' high street banks. When the opportunity arose, in 1934, the bank purchased the Penarth branch premises.
Following the merger in 1970 of National Provincial Bank with Westminster Bank, Penarth branch began to trade under the new name of National Westminster Bank.
Branch manager Neil Vincent said: "Thank you so much to our customers for helping us to mark the occasion. This is a big milestone for us and it's important to look back, but at the same time we are looking forward and ensuring that we adapt to meet what our customers tell us they want from us. Staff at the branch have 97 years' banking experience, so between us we are almost as old as the branch!"