I put this topic up again in this area because its a more technical section of the forum.
As Uplinker pointed out, I'd had no luck in the 'historic' section.
I have asked around both directly and via various forums and have drawn a complete blank...which leads me to conclude that there was no angle on the Viscount engines, they were parallel to the fuselage centre line.
The appearance of a negative angle angle in some photos must be an optical illusion, probably created by the shape of the cowl.
Problem solved, question answered by the lack of answers :-)
Juanita