Jonathan,
There are actually four boats missing, but one of those was really only a prototype to prove our new CAD system.
Shortly after the Little Auk, which was first, Dad designed the Great Auk, which was about 15ft long and more of a day boat suitable for families.
It was double ended, single chine with a ballanced lug main sail and bermudan mizzen, similar to a BR20 mizzen.
We took her to Southampton BS back in the mists of time but at the time we were only offering our boats as kits and I think this limitted her appeal somewhat. We sold the prototype to a nice bloke up in the lake district, but cant remember his name. Look out for a lug rigged boat up there with a distinctive great Auk bird on the sail. Choosing a name of a bird that was extinct might have been a bad omen, in retrospect.
Some time after the great Auk, and after the sandpiper, we developed the Razorbill which was a transom sterned "expedition canoe". It was again a non starter comercially but a valuable lesson in not developing anything too niche. I had a lot of fun sailing her.
The last boat we actually developed for production was the dabchick, a boat for children. My Dad designed and built one for my five year old brother, before he actually started SB. He was surprised that Ben could keep up a good pace under oars due the fantastically light weight of the boat. We made quite a few of these as kits but in the end the market seemed to be full at relatively modest numbers and sales tapered off.
The last boat missing is the Shelduck. She was never offered as a kit but was designed as the smallest (cheapest) boat that could prove our new CAD system and its method of unrolling developable surfaces. Up to that point we generally had to build a full size prototype and take templates along the way. We this new software we could design everything and know it would fit together perfectly. It worked really well and after that all design work was done on the computer. We still have the original Shelduck here - I use her as a tender to get out to my mooring,though I was forced to paint her pink as a concession to my young daughters.
I think that completes the list.
Matt