The safety valve bonnet has rotted through releasing the steel forming ring on the County. It is unusual to see " Double Heading " on the line between Paddington and Bristol but here we have Laira's 1012 , " County of Denbigh " pilot to a " Castle " heading westwards from Chippenham on a " down " express.
The reason for two engines may be that this is a way of getting one of them home following an " unbalanced " working up to Paddington as the " Castle " would normally be quite capable of handling this train unassisted.
The " Castle " has the mechanical lubricator reservoir on the side of its smokebox .
Possibly the " Castle " isn't too healthy and perhaps the " County " has been put on at Swindon ?
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