Aquabell boats were built originally by Bell Boats of Brundall from the early 70's. You are right in the original design was by R Tucker along with the Lochin's and probably the Nelsons.
I've been doing some research about the Aquabells and from what I've heard the original hull design by R Tucker was a 27 foot hull. He then designed a 33' hull which became the Lochin 33.
The Aquabell 33's are an extended 27' and the 28' Aquabell are a shortened 33'.
I think when Goodchild Marine started the construction the Aquabells they made slight alterations to the hull?
Would be curious to know where the designs for the characteristic wheelhouse came from.