in the 1880's there were three streets that ran parallel to, and between, the Newport Road and the Grand Union canal. These were High St, Middle St & Top St, by the mid 1930's Middle St had been renamed Spencer St and Top St had indeed become Bridge St. Since then of course there has been further redevelopment and it would appear that all of the original Middle & Top St's have been demolished, although Bridge St & Spencer St are still there the bits that are left seem to be parts that were built sometime between the 1880's & 1930's. Where the original parts once stood has now been replaced by house's and flats that are known as Permayne.
I believe the original railway houses built in the 1850s were named Top Street - this was the row closest to the canal and the highest up the hill - Middle Street and Bottom Street.
They were built in 7 blocks between what is now called Bradwell Road, which comes down over the railway and canal bridges from Bradville, to the east and what is now St James Street to the west. Where St James Street is was the western boundary of the land the railway company had acquired.
There were two north-south streets running from Newport Road up to the canal - Chucrh Street which ran along the eastern side of St James' and Glyn Street (named after a railway company personage, cf Glynn Sqaure in Wolverton).
Looking at a plan of Stantonbury/New Bradwell (the buses still had Stantonbury on their destination boards as late as the early 1960s) that says it dates from 1860 at the northern end coming south, between Church Street and the boundary there is firstly St James and then the Church Schools - now the Community Centre buildings. Then two terraces with a narrow alley between them, then two more terraces again with a narrow alley between them and finally a single terrace with a back alley.
Between Church Steet and Glyn Street there are again three blocks with alleys but these blocks have more houses and are wider.
Then between Glyn Street and Bradwell Road we only have two blocks, the single row by the canal isn't built because the canal curves and there isn't enough space.
The road between the topmost rows and the southern side of the middle blocks is marked a Bridge Street - this was originally Top Street.
The road between the middle and northernmost blocks is marked Spencer Street and it is one of these blocks that still exists today and are Listed. This was Middle Street.
The northern side of the norhern blocks is marked High Street, which was Bottom Street. The railway houses were only built on this side of the High Street - if you look at the High Street today you will see a different style of Victorian buildings.
All the railway terraces have gone now apart from the Listed block at Spencer Street, which is pedestrian only. Modern housing including the terrace called Permayne built on the land. There is still a road called Bridge Street which is modern housing.
New Bradwell Heritage Group's website
http://www.mkheritage.org.uk/nbhg/ has a virtual tour and lots of information about New Bradwell.
Hope this is of use.