Well it wasn't any angine mountings and as it got gradually worse over the following week I got the chance to have a proper look and found thet one of the P-bushes (OSF) had failed completely! It was not the rubber bush but the steel surrounding has snapped completely.
20181206_202109 by Graeme McNulty, on FlickrI fitted these and the front bushes to each suspension arm completely by the book including their orientation with relation to the arm's horizontal position. Well, as far as I know I did the job right.
I opted to replace these with 2x full new front arms because I just wasn't sure about some mistake I could have made (and the new arms were only a small leap further in cose than a full new set of bushings)
20181206_202542 by Graeme McNulty, on Flickr..I love a new bit in an old car...
20181206_211403 by Graeme McNulty, on FlickrAnyone have any views on this failed P bush? yes, it sure was off Ebay but was from what I thought to be a reputable brand, Bilstein I think they were.
If I did something wrong on the installation of these - what would it have been? Incidentally, the NS P-Bush was completely fine when I removed the other arm.