These services were introduced on the 21st July 1974, replacing the 433/434 Uppermill circulars and most journeys on the 437 (Mossley to Diggle). Their introduction gave Diggle its first ever through bus link to Oldham and restored the similar link that Delph village had lost with the cessation of the 160. That link was never very frequent anyway.
The principal routes were the 431 and 432, which were the opposite directions of the same service, numbered differently to avoid confusion in Oldham town centre. It would actually have made more sense to split the through service in Oldham as the through link served no useful purpose, but it was perhaps considered that the links previously provided by the circular bus service should be retained, even if they were no longer convenient.
The 431 went from Diggle to Carrcote and 432 Carrcote to Diggle. Both these routes served Dobcross village but certain buses did not go that way but took the direct route from Uppermill to Diggle past the Navigation. These were numbered 433 (equivalent to the 431) and 434 (equivalent to the 432).
The latter two services did not continue very long as by February 1975 all journeys went through Dobcross and the 433 and 434 services had disappeared.
The next change came with the big service revision of 20th July 1980. This saw the introduction of the 355, which replaced the Oldham to Carrcote part of the service, which now became just the 431 running from Oldham to Diggle. It lasted in this form until deregulation on 26th October 1986.
The service was operated by Greater Manchester Transport, mainly with single-deckers, but later at least one working in the evening peak was worked by a double-decker on Fridays only - see the picture in Dobcross. In later years the 431 service saw regular use of double-deckers, as this collection shows.
© David Beilby