The D20 is also an ebay win. She seems to be quite old, maybe early to mid 80s. She looks a bit worn but she runs quite well.
As the D16 has the same cylinder and is a better runner she will nut be steamed up often. She has a bigger boiler, a pressure gauge and a priming cock. She is the last of Wilescos medium size Engines.
The preowner has not been very careful. There are true sediments in the boiler. Beside a vinegar cure she will need some steamups to get her "lungs" free. it seems to work. Second and third stemup were better than that you can see at the video.
She is too small to asign her to the big Wilescos and she is too expensive compared to a D16 that does the same job.