You get the cash. It has always worked this way.

This is a way of 'selling' Avios back to BA if you want to cash out. All you need to do is find a route where BA currently has a promo on 'part pay with Avios' and you can get up to 1p per point.

For obvious reasons I have been sitting on this rather than broadcasting it via HFP.

I'm not entirely sure what the problem is here. Oxon Flyer was happy to sell his Avios to BA for, presumably, something like 0.8p. What has changed?! If he chooses to book another BA flight, he can use the extra cash that BA has now given him towards it!