Woot! Woot! Search up Buckingham McVie on this link, so you could see their Silver certification for their album.
https://www.bpi.co.uk/bpi-awards/
I was looking at their Wikipedia page to find this out, and it seems like a fan wrote it. Nonetheless, I liked that picture used from the tour on the page. Apparently, it means they sold at least 60,000 units in the UK.