Intermediate occasional block
The FR had a period in 1960 when it used an intermediate block post between Penrhyn and Tan y Bwlch. The block worked by the block man telephoning Penrhyn to report when an up train had passed so that a second up train could enter the Penrhyn to Tan y Bwlch section.
Allan Garraway admitted this in a letter to the Ministry of Transport Railway Inspectorate on 9th March 1961.
"We do not normally operate the intermediate block between Penrhyn and Tan y Bwlch, but last summer we had a period of Taliesin failing for lack of steam, and as some telephone boys were working up in that section at the time, we used them to operate an intermediate block."
This did not satisfy Lt. Col. E. Woodhouse who wrote back:
"Your timetable shows the 10.30 up train as reaching Tan y Bwlch at 11.15 with the following 10.45 up train (4th July to 10 September) leaving Penrhyn at 11.03."
In other words, a second up train was entering the Penrhyn to Tan y Bwlch section before the first train was scheduled to vacate it.
That this was standard practice is demonstrated by a section of the document "Report on train operating methods 1960". It reads as follows:
"Normally two trains follow each other up in the afternoon, with 15 minutes headway, but if the first train is late, the above mentioned visual is used. On occasions it is possible to establish an intermediate block between Penrhyn and Tan y Bwlch utilising suitable personnel with a portable telephone, and to save time the headway can then be reduced by use of this special intermediate block, who will give train-out-of-section back to Penrhyn after the first train and will hold the second until train-out-of-section is received from Tan y Bwlch."
The intermediate occasional block post was usually set up at Bryn Mawr and was operated with a portable omnibus circuit telephone as pictured on page 137 of Immortal Rails volume 1.
The ministry men were also concerned about block working being operated by train crews telephoning one another - they insisted on 'static' ground staff, not train crews, being responsible for the block working. They were relieved to read that the FR had introduced a controller at Portmadoc. On 15th September 1961 Woodhouse reported:
"Regarding our endeavours to impress on Garraway the need for a satisfactory system of block working for following trains, other than by means of phone messages exchanged between train crews, I was glad to see in a note in the society's London Area Group newsletter for August 1961 to the effect that train arrivals at intermediate points are now reported to a controller at Portmadoc, who also gives permission for the second train of a pair to depart."
The Ministry seems to have had its ear very close to the ground! It is an interesting insight into the responsibility of FR Society Group newsletter editors.