Aspect Ratio Issue

[Robert the Bruce]

I have a Sony HXD970 DVD Recorder/Player and a Panasonic TX-32LXD70 TV and a Sky HD Box.
Sometimes (most of the time) when TV channels broadcast older TV shows or movies the aspect ratio on my TV changes to 4:3.
I'm not sure if the TV stations themselves are broadcasting the older material in this format or not. However, if I go for my TV remote control and change from AV to TV so that I'm now watching the TV through the Television itself rather than via the DVD Player/Recorder I find that the screen size is now 16:9.
In other words, the aspect ratio using the TV ONLY is always 16:9 but if I change back (by pressing AV on my TV remote) to the DVD Player/Recorder the ratio is 4:3 (in older programme's/shows/movies) and after looking through the manual it seems there is no way to change the aspect ratio to 16:9 on the DVD Player/Recorder.
Anyone any ideas on what (if anything) I can do ?

[DB83]

The Sky Box does have various picture settings but I would expect that over hdmi you get a full HD screen ie 1920*1080. It is the tv broadcast that then determines how that picture should look.

For example, BBC have been showing older Disney films and they are shown as 4:3 with borders left and right. That is how they should be shown.

If you see that same broadcast full-screen then your tv or even the Sky Box is not set up correctly.

My dvd recorder (a Sony) does have a setting that controls playback. It asks for the tv type so that should also be set as 16:9