If I said that station A is 2 miles directly northwest of station B, and they are both on a train-line which forms a complete circle, to get from A to B would it be best to set off clockwise or anticlockwise - you have no way of knowing without knowing where on the loop the two stations are. In which case, you'd also know which compass direction you'd have to set off in.

You can see it if you look at a geographical version of the tube map and I suppose the standard map suggests it. But it had me stumped.

What do they do at Aldgate where the standard map suggests north / south travel, althought the actual direction of travel is northwest / southeast?

If that's the case, wouldn't using "clockwise" and its opposite by definition be less confusing on the Circle Line? And it seems to me if the Circle Line from Moorgate to South Kensington didn't exist, signage towards Liverpool Street could just as easily say "northbound"--or simply "Liverpool Street", for that matter.

(Apologies for jumping so far into this debate from so far away. In a previous life I was the associate director of the New York City Transit Riders Council, so I find public transport signage discussions fascinating.)

If the western part of the Circle Line didn't exist between Moorgate and South Kensington, you would still have to set off Eastbound for both directions of travel, but you wouldn't expect it to say Clockwise or Anti-clockwise in that situation, because it would make no sense. So why find it be any more confusing with a complete circle?