Links to GB trainspotting logs can now be found at the following address
I have only a few photos of these workings; all from S Wales. I moved there in Jan 1979, and the Port Talbot – Llanwern service changed to pairs of 56s in the summer.
I never saw the Hunterston – Ravenscraig workings.
Here are 37303, 37304 and 37307 on the loaded train in Nov 1976.
And 37299, 37302 & 37305 in the spring of 1979.
The locos involved were fitted with strengthened couplings. Therefore it was unusual to see anything other than 37298 – 37308 on these trains.
However, a couple of other locos were also fitted; one being 37241 seen here with 37300 and 37305 in 1978.