Rents for shops do not get any lower than they are in Westbury. So any talk about rents being too high in Westbury is to simply confirm that there is no understanding of what makes a retail business in Westbury tick. Rents in Westbury are at rock bottom compared to other retail centres.
I thought that there is a deli counter in Morrisons. I can't see any independent shop in Westbury competing succesfully against any big supermarket chain because they just won't have the turnover to buy stock at cheap enough prices.
Most folk just do not understand the way the retail market works. You can't look at a High Street and think that just because a type of shop is missing that there is an opportunity for a shop to come along to fill the perceived gap.
You need to look at where current residents are doing their shopping. In Westbury's case it is mostly in Trowbridge, Warminster, Frome and Bath, with some happening in Westbury itself plus a few other places where some folk happen to work such as Chippenham, Swindon, Salisbury, Bristol and even Bournemouth etc. You then need to consider whether those existing shops in nearby towns would gain any economic benefit from opening another branch in Westbury given that this might mean losing turnover from their existing branches - in almost every case the chains just won't come to Westbury because they would make a loss overall rather than more profit.
In the case of major supermarkets, the economics work a bit differently and almost any supermarket chain would come to Westbury if it could find a site upon which planning permission is possible for another supermarket. Planning rules exist to cap the total floor area for supermarkets in any location. Westbury is at its limit and so there will be no more supermarkets or supermarket expansions in Westbury for a long time.
Independent shops that are not simply providing a small local service (hairdressers, estate agents etc) tend to open in Westbury where the owner probably has no idea about the scale of the mistake they are making or because the rent and outgoings are so low to start with that they can afford to test whether it works and then close the shop if they decide they can't afford all the losses any more. Sometimes, independents actually are appreciated in Westbury so they struggle on ...
At the end of the day, Westbury will never have a shopping system that other towns of the same size tend to have because it has such a small hinterland and three other larger towns are nearby and are simply sucking custom away. This cannot be overcome and the situation will simply carry on getting worse especially as more shopping will increasingly happen online.
I think the only way that things in Westbury could improve is if the Morrisons is reconfigured so that the main entrance is in the High Street itself so that the supermarket and the High Street work with one joined up mall and car park. This will need a developer who believes in the project to drive it along. There is simply no-one within the relevant local councils with the understanding or finance to make any progress. They will simply attend courses and seminars that talk utter nonsense with examples using other towns with different circumstances to Westbury (eg. a much larger population with a much larger hinterland as well - eg. Frome).