Alice and Alice Too
The annex, amusingly named Alice Too, consists of a removable bow section that fits around the existing bows and is held on by wires and straps. Alice Too appears to be heated (it has a chimney), probably by diesel since the extension has vented dollies and a fuel filler. I assume the dollies are used for mooring Alice Too separately.
Attachment of Alice Too
The rest of Alice appears to be a well-equipped conventional narrow boat with a very nice paint job.
We couldn't stop to investigate the boat further so all we have to go on is my photos. Looking up her details on the Jim Shead database Alice appears to be registered with BW as a 70ft boat - that's presumably both parts. I assume that the owners wanted extra accommodation but still wanted to navigate waterways with shorter locks. Having two sections could also help with moorings. Imagine turning up at a congested mooring, splitting your boat into two sections and mooring them up separately!
Certainly a unique boat or should that be boats?