Steam Engine Linda on the Ffestiniog railway in 1978

This is a picture of the Steam Engine 'Linda' which was taken in 1978 at the site of the Ffestiniog Railway in Wales. It is shown pulling three carriages and is presumably just leaving or just about to arrive at the station. Unfortunately, I don't know the exact date of this picture - it just has written on the box 'Trevor 78' which I've assumed to mean the image was taken sometime in 1978. That actually seems quite likely because the Orwo film used was popular at that time.