But it's not what he (allegedly) did, but with whom he did it! And that's where comparisons with BB and Peter H fall down. In both their cases, the "other woman" was a civvy.
Not only was this not so in this case, but the "other woman" was a serving officer, and wife of a serving officer. Most importantly (IMHO), she was his direct subordinate - he was her 1st RO for pity's sake. No tendency to overmark there then!
And I think Peter H would have got away with it these days .... if you recall the details, it was a journo stitchup that made it public - quelle surprise!