Thanks for the reply.
I should have said that front and rear wheels are both 700. My judgement about the frame top tube not being horizontal is based on running a plumb line and a spirit level over the frame as the bike stands on a level floor. So yes, you could be right that the fork (standard Columbus Tusk) might produce the impression of the slope from ST to TT. But given that my impression may be correct, my concern was whether this was:
a) Likely to be an error in the frame construction about which I should be concerned, and
b) Whether this geometry is likely to cause any particular ride characteristics about which I should be concerned.
Yours,