Linda Burton, who has worked behind the counter for 25 years, and Vi Wilkinson, who has been there 10 years, cut the ribbon to open the post office in Southwick Square.
They were presented with flowers by sub-postmaster Sameer Philips, who said they were his VIPs and without them, the post office would have been shut a long time ago.
“Without them, I couldn’t have run the post office and I really owe them all my life,” he added.
Mr Philips has faced more than a year of difficulties getting the post office and new pound shop fully up and running. For months, people had to pass through the an empty shop to reach the post office counter at the back.
After dealing with myriad legal issues, a tenancy in common agreement was formally handed over three weeks ago, which meant Mr Philips could begin work on updating the shop.
He said it was now totally transformed and it was difficult to believe it was the same place.
Southwick post office was originally in Brighton Road, where it was run by Mr and Mrs Lewis-Ford. Mrs Lewis-Ford’s parents were the first postmasters.
When Southwick Square was built in the early 1960s, all the shopkeepers from Brighton Road moved there, along with the post office.
Glenys Lewis-Ford took over the business when her parents retired. She was appointed sub-postmistress and continued to run the jewellery shop there, too.
Miss Lewis-Ford died unexpectedly in March 2011, the last of the original Southwick retailers and the third generation of postmasters.
Her death resulted in many legal complexities over probate and other matters.
Mr Philips, who runs two other shops in the square, had expressed an interest and managed to keep the post office open, with the support of Vi and Linda.
Mrs Beryl Ferrers-Guy, who helped organise the official opening, said: “Throughout the never-ending legal saga, both these ladies faced working in the most appalling conditions as a result of the shop fittings being removed by the executors of Glenys’ estate, creating a concrete cavern with little lighting, even less heat and masses of dust.”