Tee Emm - I second SNS3Guppy's "bug" position as standard in Boeing FCTMs.
Or at least, for the Boeing aeroplanes of my generation.
A "double white bug" is, in the 747 (and 737 - or even 727) set on Vref.
As to flying within 1 knot of speed - you are much more proficient than me.
On a good day, I was able to achieve +/- 2 (?) knots accuracy when hand flying.
That is, if I was not too tired.
Maybe you are using Lufty standards - one/half of a knot...?
I suspect that BA is certainly of equal standards to LH's...
Happy contrails