To mark the day, staff at the branch in High Street invited customers to share their specially-made NatWest celebration cake, while younger customers tucked into the anniversary sweets.
The branch was opened in 1836 by National Provincial Bank of England. The bank had been founded in London five years earlier, with the intention of establishing a nationwide network of branches. Porthmadog was a relatively new town, having only been founded in 1811 by William Maddocks after he reclaimed a large part of Traeth Mawr from the sea for agricultural use.
The diversion of Afon Glaslyn had created a new harbour area, and the first public wharves were built in 1825. The rapid foundation and expansion of Porthmadog, coupled with the ongoing construction of the Ffestiniog Railway, attracted the attention of the bank's directors. As a result, the bank's Porthmadog branch opened on 25th May 1836, under the management of Captain Richard Prichard, a former sea captain who had settled in the town. Whilst the branch's original location is not known, by 1869 it was trading from premises in Bank Place.
During the second half of the 19th century, Porthmadog expanded rapidly and its population more than tripled in size between 1821 and 1861. The harbour area became increasingly important, particularly for the export of slate following the construction of tramways to the port from local mines during the 1850s and 1860s. The harbour was also used to export copper and lead ores, timber, bark and wool.
The town's expansion caused the branch to flourish, and by 1879 it had outgrown its premises in Bank Place. Suitable land for a purpose-built bank building was found in High Street, and the move was completed by 1881. By the early decades of the twentieth 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 to form one of the emerging 'Big Five' high street banks. The new merged bank became known as National Provincial Bank.
In 1968 National Provincial Bank and Westminster Bank, along with National Provincial's subsidiary District Bank, announced their intention to merge. The banks' operations were combined over the following 18 months and they began to trade as National Westminster Bank from 1 January 1970. Today, Porthmadog branch continues to serve customers from its premises at 72 High Street.
Branch manager Geraint Owen said: "Thank you so much to our customers for helping us to mark the occasion. Staff at the branch have 142 years' banking experience, so between us we are almost as old as the branch!"