Yeah the first two novels were credited to their "Grant Naylor" partnership, and they're both excellent.

After that, they each wrote an additional Red Dwarf novel individually / separately. Personally I've never come across those last two novels, although I always check for them whenever visiting a used book store. Maybe they were only released in the UK. They're available on Amazon in the US, but I haven't quite given up hope on stumbling across them naturally yet...

Somehow enough fragments of that stayed in my brain since 2004 to google it. My first and last real-life encounter with the word 'gestalt'.