The issue has been reported to WC.
I have received the following from a member of Semington Parish Council.
"I'm writing to make you aware of a serious problem on HILP17, the bridleway that runs along the canal.
A large sinkhole has developed over the weekend. This has been reported to Wiltshire Council via My Wilts, but I thought that I should also make you aware so that you can warn the residents of Hilperton to take care.
The sinkhole is located in the field after the winding hole if you are walking from Semington towards Whaddon lane (it's close to the gate as you enter the field from Semington).
The hole is approximately 30cm wide and 70cm long. It is difficult to estimate the depth, but it looks to be over 1m deep."