But sometimes you just have to take things as a guide rather than an absolute.
Take this, for example:

Shaded, up in the trees, a road sign, clearly showing a 'One way' - so you could use either of the two lanes.
Exhibit 'B' M'lud:

Unfortunately, it was a quiet day, and I only just got the camera ready in time to catch the back-end of car heading left > right.
Yup, against the traffic sign . . .
For those who don't know the area (and there's no real reason why you should), this is the Park Way area, currently undergoing a massive development. Previously it had a one-way circulating around a parking area in the centre . . . but when that was closed off this sign was left behind!
Of course, even if there was a one-way still in place, that doesn't mean that traffic won't go the wrong way!
.