The first is from Queen Victoria's golden jubilee in 1887. It would probably fetch £20-30 on eBay. The second is from the coronation of George VI. This would fetch under a fiver.
Weirdly, the George VI piece is probably rarer than the Victoria piece. Everyone knew Victoria's jubilee was coming up, so factories churned out commemorative wares by the million. George VI was crowned unexpectedly, though, following the abdication of Edward VIII. The factories didn't have much time to make anything in advance, so there wasn't as much available for the discerning collector of tat.
My mum has now given the mugs to me. I'll discuss with my wife which cabinet we're going to forget about them in.