Openreach just dug a hole...

....outside my house.

We already have FTTC twins next to the 2 nearest cabinets, and this hole is just near an existing BT manhole cover.

Any idea what it might be?

http://i.imgur.com/tqfObE5.jpg

Well that could be absolutely anything!
Could be for a repair, where a request for a new jointbox has been requested when the repair is completed. They could have been pulling copper or fibre and encountered a blocked duct. They might then smash the duct open and fit a jointbox afterwards for easy access in future.

A burial ground for defunct keyboards.

All fibre/copper runs seems OK, as FTTC is now established in the area. Hence my curiosity!

Check www.roadworks.org if it shows permits for works in your area. If it does, the description should give you an idea of what's going on.

Tried that first, no sign of any works listed there. now or for the next 3 months.

There's a permit number on the OpenReach signage though. Maybe something boring like another manhole