The Neptune was reportedly in what's now the pier pavilion. It was first licensed on March 14th 1960, when the license from the now-defunct Grand hotel was transferred to it.

"The Neptune Bar was on lower left of the Pier building (now owned by Ipswich Salthouse oeners). It was popular with bikers and hippies and often had discos. Don't know when it closed but I can remember going in it c1972" Martyn Elmy

"In about 1982 it was renamed "Mariners" and traded for a couple more years." Martyn Elmy