Mr and Mrs Day celebrated their golden wedding with a dinner for about 250 friends at Clarence Pier Pavilion.
The couple started a family business before eventually becoming lord mayor and lady mayoress of Portsmouth for two years.
Frank Miles said: ‘It was the most successful partnership in the fullest sense.
‘They carved their niche into the history of this city in both their public and private life.’
The couple were presented with a crystal inscribed goblet on behalf of 40 of their friends and citizens of Portsmouth.