Have you spoken to any planners, a quick search for similar applications in other LAs might be a useful thing for them.

There's a Royal Institute of Town Planners, they probably have a magazine you could advertise in (but equally that might get you blocked, idk).

RICS people could probably use the data too? I guess it's useful house-buyer info; houses in the vicinity had successful loft conversions, say.

On the data side - it's something of a moat for you now, but I could see you being successful with FOI requests. An MP might be interested in championing open data access.

All good points. I've been so busy with the data collection and just "irl stuff" that I haven't spoken to planners directly which is an oversight on my part — they're the obvious power users. RTPI/RICS are both on my list but as I said, I've been focusing on data more than distribution. Probably the wrong order tbh. FOI is interesting, especially for the trickier portals (Liverpool's WAF, the dead-portal ones). It might be cleaner than scraping. MP/open-data angle is definitely something I hadn't seriously considered. Worth thinking about tho! Thanks.