Thanks to the people who have contacted me about this.
As advised to them in my reply emails, I can confirm that this work was towards part of the more detailed information required by Wiltshire Council from the applicant.
The work was to assess archaeology in the area and I expect that further work to establish water table levels and drainage rates will be required too.
There is still much information required from the developer and I suspect that no decision will now be made until the autumn.