Came across this photo of the Hawthorn Leslie (Engineers ) Ltd site at St Peter's on a Tyne and Wear Museum's website. Photo taken by Turners (Photography) Ltd in 1957.
Ron, there were no cargo quays in this part of the river. Newcastle Quay is just off photo to the left. As regards ships alongside at Hawthorn Leslie, I don't think they fitted the engines alongside. I think they were transported (by road?) to Hebburn etc. If so were they assembled and tested at St Peter's then taken apart for transporting elsewhere, I presume so.
Just to make sure I've got it right. St. Peter's was on the north (Newcastle/Walker) bank of the Tyne. Presumably where St. Peter's moorings now are? (Whereas, the main HL shipyard was at Hebburn on the south bank.)
Also Ron, you mention the St Peter's moorings or marina. As there was no pre-existing dock there to make a marina, I had it in the back of my mind that the marina was the site of the old engine test bed. But that could be a load of old ######.
You'd have thought that it would have been easiest to put a small quay and crane there and barge the engines down and across to Hebburn. Rather than a road trip via the Tyne Bridge and through all the Newcastle and Gateshead traffic. Maybe there was one in the past.