Archaeology sighting

I was on the no 35 bus up to Lauriston Place, to donate a pint of me finest, when I spotted a small amount of archaeology going on and thought I'd blip it for D, as he likes to know what's going on. Looks as if they're going to install a septic tank for Queen Mary's bath hoose (just out of shot to the right), but probably not.

Was supposed to go out to see a friend's show in the evening but felt somewhat dozy and just sat on the sofa.