My Humax PVR is connected to the TV by HDMI but there is no audio at the TV. Am I missing something fundamental? Does the Humax output audio through the HDMI?

Yes, the Humax should output audio via the HDMI.
Have you had a sound system connected to your TV and altered your audio set-up for it?

You can set the Audio out via HDMI to either Analogue or digital. try switching it may be your TV that wont accept the digital audio signal. Also do you have the volume up on the Foxsat or down on the TV, silly question I know but eaqsy to forget

Thanks guys!

It seems to have been finger trouble! I switched the HDMI lead round and all is now well.

I am suitably embarrassed.