A joint service between the two towns started on 6th March 1932 but had initially to be worked entirely by Caerphilly UDC as Pontypridd were short of vehicles.
The opening of the first factory on the Treforest Trading Estate in 1938 started an increase in traffic on this service - by the end of 1939 there were 60 firms trading on the estate. It appears that the the route was converted to double-deck operation in the early war years, which involved checking clearances particularly at the bridge under the former Rhymney Railway line at Beddau Loop Junction.
The service seems to have maintained a similar timetable for many years. As one bus was sufficient for the hourly service it was the practice to share workings. For a long time this meant that Caerphilly worked the service in the morning and Pontypridd worked in the afternoon. There were also periods when Pontypridd worked mornings one week and Caerphilly worked afternoons then alternated such that the following week the working pattern would switch over with Pontypridd doing the afternoons. This pattern continued long after local government reorganisation saw it become a joint service between Taff-Ely and Rhymney Valley and probably until the end of joint operation. One consequence of this arrangement was that during periods of alternate week operation the last bus from Pontypridd to Caerphilly only ran on alternate weeks, except on Sundays when it would appear the service was worked only by Caerphilly/Rhymney Valley.
The route was straightforward, from Pontypridd going via Treforest and Nantgarw then into Caerphilly. The only change of any significance was to the terminus in Pontypridd. originally this was on Sardis Road but in latter years was at the bus station. For many years it was the only Taff-Ely service to use the bus station.
© David Beilby