The two British mirror in lid sets sold recently by Bonhams that come to my mind are a Baird T-5 and a Marconi 702. Both of which sold for hefty sums, and I believe both to the same buyer in Canada.
Marconi: $26,000+
http://www.bonhams.com/auctions/19034/lot/1/
Baird: $43,000+
https://www.bonhams.com/auctions/19798/lot/1/
What a thrill it would be to watch your set sell at auction for those prices!