Yep.
As it's live, the other mics are partly picking up the bass track and mics (such as the guitar mics) are facing roughly 90º and 180º from the bass amp.
It's positioned facing 45º from the keyboarder/backing vocalist, and his amp is 45º*from him facing directly at the bass amp.
The Kick drum mic will pick up (due to the way bass frequencies curve round) roughly 180º out of phase bass. There's another guitar amp to the right of the bass amp (270º), an overhead behind the floor tom, and above the clash cymbal/snare which are both picking up the bass.
And as I learned, the Rode NT1A's polar pattern is anything but cardioid, it's picking up lots of bass (which a low cut takes care of mostly!).
So it seems that next time, the bass player will be monitoring through headphones if I have anything to say about it haha!
I'll try the sample delay and see how I get on!