I know that Tescos have plans for the Boundry Hall site, but it isnt really nessesary to have another supermarket in Tadley. Sainsburys is adiquate for most items, there are several local shops dotted around and I have thought that a a new development on Boundry Hall would bring an increase in traffic.
A much better use of the Boundry Hall site would be to turn it into some nice open space. I'm sure the residents down the adjecent road would prefer to look out of their windows to a large recreational area than the backend of a Tesco.
alex posted a couple of photos from Boscome Gardens, i've been there and it is a very nice place. I think something like that would be much better for Tadley than another large shop.
_link_ to alex's post