Groundworks in Warwick carry a consideration that most towns do not, and it is worth raising before anybody is committed to a programme.
In the historic core the council may attach an archaeological condition to a permission that involves excavation. What that means in practice is that the dig is watched, or investigated first, and that costs both money and time. It is not a refusal, it is not unusual and it is not a reason to abandon a project. It is a reason to have the conversation at the budgeting stage rather than when the machine is standing idle.
The second factor is what you are digging next to. Buildings and garden walls of this age sit on very little foundation, built in lime mortar and entirely intolerant of a trench opened alongside them in one go. Excavation next to them is sequenced, sometimes supported, and never rushed for the sake of a hire rate. Where the wall is shared, that is party wall territory.
Third is the ordinary one. On shrinkable clay a foundation near a mature tree goes deeper than standard, and in a conservation area that tree is protected as well. A trial hole answers this before an open trench does.
Everything is inspected before it is covered. Our footings and excavation page explains how we approach foundations and site preparation.