I understand that the last remnants of RNAS/RAF Felixstowe has been demolished on the Landguard Terminal at the Port of Felixstowe, this was known as 22 Shed locally but was one of those very large Seaplane/Flying Boat hangars
This is a recent panorama view of Landguard, one hangar demolished
Every aircraft evaluated for the RAF/RN/FAA was checked out here that had floats or a hull, this photo courtesy of Felixstowe Museum shows the three huge hangars, the slipways and the pier with a Titan Crane that could lift loads in/out of the water to 50 tons, photo to follow
A Sunderland Flying Boat can be seen and above that can be seen the Titan Crane
An interesting piece of film footage here from 1959 when a HAR/SAR was based at 22 Shed the old flying boat hangar, obviously a practice this one but some recognisable shots for me on this 11 minute clip