"I find it rather odd that, having the [auditors] been fined a nifty £15m for not properly doing what was expected of them ... that this Lynch chap is still on the hook"
The fine actually puts Lynch _on_ the hook. Lynch was required to behave lawfully, auditors or no auditors. His argument was "the auditors said it was OK, so it must have been OK". His problem is that the fine can be construed as the regulators saying "the auditors were wrong to say it was OK".
OTOH, if the civil case finds for Lynch, then it is going to be _very_ hard to argue that a fair criminal trial could find against him (because the standard of proof is so much higher in a criminal case). I presume that if the civil case finds against HP they will try to appeal, and they will try to use Deloitte's fine as part of that appeal.