Interesting find, Brummie; one doesn't see too many Mercurys so minimally equipped, yet with a "comfort" saddle. A true stealth presentation, too, with no head badge or logos visible.
Doesn't look like it was a good fit for the last user (apparently long-smallish frame with long stem and seatpost well down in the tube), but I get the sense there's a story behind this.
It'll be interesting to see how it goes. It'd be nice if someone here has the winning bid so we can learn a bit more about it.
Best,
Dan. (...who thinks every bike has a (hi)story; we just don't always hear it)