From Airbanda's post above:
Some V802s were withdrawn then including at least one that was scrapped for spares at Leeds. Thereafter operation was a mix of 802 and 806 variants.
I've a vivid memory of standing on my bike saddle and peeping over the fence to the apron outside the hangar that used to be to the left of the terminal at LBA, sometime in the early to mid 70's. There was a Viscount in BEA/red wing livery sitting on it's belly in the process of being scrapped. Twas before my spotting days so I didn't get a reg.
Could have been G-AOHH or 'HK according to VVN.
I've an idea the 806 variant was built with more powerful Dart engines for certain hot/high or otherwise operationally difficult BEA duties. They were changed to the same version as the 802 when the machines passed to Cambrian/NE, becoming the 806x as mentioned above. Might have been some other detail differences in internal layout too.
True - most 806's were re-engined down to 802 standards.
I think the catering layout internally was slightly different between the 802 & 806, and that led to the one external way of telling the difference - the position of the single window behind the forward door. Further back on the 802.