@ach2 - thank you for your comments, I have checked and the box is HDCP complient. I would be surprised if the Sony DVDRs were not as I understand they were major partners in the specification.
@notoriousdbp - "If you have YouView, do you need 2 DVD recorders?" Is judgmental and in no way a technical answer.
Perhaps if you took the tv out of the set up everything would be fine ,after all do you need it really ,buy an e/reader ..JOKING
So the fault is with the Humax youview box.
I wonder if Humax Tech services will ever bother to reply to my email asking if there is a problem and if so is there a fix now or in the future.
Presumably the same applies to the BT Vision box.
Yes, looks like it is just the Humax box.
I would hope they fix this as it effects everyone using HDMI as you have to manually switch the TV to right HDMI channel at the moment. YouView seem quiet good at releasing software fixes so fingers crossed.
Response form Humax
"Thank you for contacting Humax Support.
I'm sorry to hear that the YouView box isn't syncing correctly with your HDMI switch. The YouView box automatically carries out the handshaking and has caused this problem you've experienced. Unfortunately as this is a BT box, this would contain their software and as such I would recommend you contact them in regards to both of the boxes as they would be able to give you a more accurate insight into resolving this issue you've been experiencing.
You can contact BT at 0800 800 150 or quite simply at 150 through a BT landline.
Humax Customer Support"
So no further forward as the people on 150 do not know a HDMI from a DHCP and I am reliably informed by an engineer on that number during a previous call that BT Vision and Youview boxes do not use TCP/IP but a special propriety transport protocol developed by BT and the specification is secret.
I ran into a similar problem with a Sky HD box set to 1080p, it seems to be down to the quality of the HDMI signal. I found that using a better quality/shorter cable fixed the problem. Even though my Blu-Ray player worked quite happily on the original cables at 1080p, the sky box wouldn't have it, the YouView box could be suffering from the same problem. Try dropping the output resolution and see if it then works, if it does then it sounds like the same problem I had.