Clutch bleed pipe and nipple nut sizes?

[Juddder]

Can anyone remember or help me out with what size spanners I should be using to loosen the clutch bleed pipe nipple from the clutch bleed pipe please?

For the nipple, 6mm is too small and 7mm is too big, which leaves me fearful of stripping the nut = world of pain

6mm



7mm



and the pipe nut has the same issue in that a 14mm is too small, and a 15mm too big which again could round off the nuts = more world of pain

14mm



15mm



I'm guessing that must mean they are imperial sizes, but that would seem strange on a car build in 1996 or so?

Thanks

[Juddder]

I'm going to hazard a guess that these nuts are imperial as

1/4 INCH = 6.35 MM

And

9/16 INCH = 14.29 MM

But if anyone can confirm that would be great