Okily-dokily... after LONG correspondence with Humax and Channel 4, both denying that there was any issue, I got this from Ch4 today:
"Thank you for contacting Channel 4 Viewer Enquiries.
We appreciate the time you have taken to get back in touch with us and we are sorry to read you missed the first two minutes of this programme.
Please be advised, engineering have identified an intermittent issue and are speaking directly to Freesat around this.
We would like to apologise for any inconvenience caused in this matter, we had been told that this issued had been resolved.
Please be assured, we will get back in touch once we've any further information."
So now we know.