With thanks to Bob Burge and Mark Simmons, the news today is that:

Contractors for Thames Water have exposed the sewage pipe and confirmed that it had collapsed. They advised that the break did not appear to be confined to the immediate area of the inital break but extended back for an as yet undetermined distance, in the direction of the island at the junction of Chiltern Hill with Ellis Avenue.

They did not have the equipment to proceed further during today and departed in the early evening indicating that a larger team with appropriate machinery and shoring for the walls of the hole would return on Tuesday morning.

Since the breakage has effectively blocked the line at this location, the suction tanker will stay on site throughout the night (Mon-Tues) to remove waste coming down from upper Chiltern Hill. No properties below the breakage will be affected, as the pipe in this area is intact and operational.

Further updates will follow in due course.