Cheers, Chris, I'll see how I get on with the Gangster and (another second hand fishing pole I've just bought on e-bay) if that fails, I'll go for the F16.
I know some of Squeak's best accounts involve cleaning windows above long pitched roofs while standing on steeply sloping drives; so maybe his Gangster DIY pole just isn't up for this sort of extreme work?
Anyway, I'll report back about the Gangster once I've received, modified, and used it.