The Vanguard was a surprisingly noisy aircraft in the cruise. On London to Scotland they were audible overhead the Midlands cruising along at about 20,000 feet.
It was an aircraft that was immediately outclassed. BEA using them to the Continent were swept aside by all the European carriers who introduced Caravelles at the same time. In the end they had to use them just on domestics, or colonial routes like Gibraltar or Malta where there was no competition. Air Canada meanwhile were only able to run them on because they had a regulated monopoly on most of their routes.
The Tyne engine didn't have much commercial sccess compared to the Dart on the Viscount, and must have been difficult to maintain downroute.
However you can't really blame Vickers and the Government too much for not forecasting the arrival of short-haul jets, Lockheed ran into the same issue with the Electra.