With thanks to Derek Bryan, Bob Burge and Mark Simmons, here’s the latest update as of Friday evening:

Today the Thames Water sub contractor completed the repair to the sewer and then used a TV camera to inspect the inside from lower down the hill. This revealed a further obstruction/misalignment uphill from the present repair. They will now uncover and inspect the sewer for 4.5 m uphill from the present damaged area and repair as necessary.  That may be completed over the weekend, after which Veolia will return and restore the road surface.

View of work area on Chiltern Hill