Thank you Ash.
Yes, as Ash pointed out, there is an experimental search facility that allows you to restrict search terms to addresses.
so you could try adding
location:"sandhurst" to your search term, so
search/companies?q=electrical+location%3A"Sandhurst"
Please NOTE:
It is not officially released or supported and maybe removed in future releases.
You cannot use this to find ALL companies in a particular town due to restrictions in the number of search results returned.