We have found just one other Compukit Deluxe model and it is in one of my favorite places! Bletchley Park in Milton-Keynes was the code breaking center for the Allies during WWII...and Alan Turing worked there.
The National Museum of Computing (TNMOC)is now located at Bletchley Park (I remember when it was more informal and was known as the Retro-Beep Club). TNMOC lists a Compukit 1 Deluxe Model in their collection.
[Update: November 2021. Konrad Kumor (handle "Darkon" on the retrocomputingforum website) reported in May of 2020 that he had one he was offering for sale. It had belonged to his Dad. A picture of his was included and showed some worksheets I had not seen before.] We do not know where it is now.
We would greatly appreciate any information you might have about other existing Compukit 1 computers.