Silverbrooks
I think that's a possibility now. As I understand it, The Government uses data from the Valuation Office Agency (VOA) to identify eligible households for the Warm Home Discount. The VOA matches property data with Tax Credit and means-tested benefits data.
Currently, only those eligible for various benefits PLUS living in energy-inefficient homes are eligible for the Warm Home Discount. The DWP has details of those eligible via benefits. I'm not absolutely sure who has details of energy-inefficient homes.
What I do know is that I'm not eligible because my home is considered energy efficient. That information was available within seconds at the click of a button. All rental properties are required to have an energy efficiency rating (updated periodically - every five years, I think). I believe owner occupiers can apply for a certificate. I don't know how much it costs, but it might be worth it, if you have a low income and live in an energy-inefficient home. It might also make you eligible for any government grants which are sometimes announced (but don't take my word on that). If you're selling a property and it's energy efficient, it might increase the chances of a sale.
I'm sure Silverbrooks is right and the government has the ability to match data from various sources.
The blurb on the Warm Home Discount site says that even people who aren't eligible for Pension Credit (and, therefore, don't receive WFP) could be eligible. I'm pretty sure that I would be eligible if I lived in a more inefficient house. That's probably why they don't roll the benefits into one.