Use of 'tag only' on existing files.

[Jimmy Aitken]

I'm trying to work out how to tag a load of files that I have without
tags, but the programme information is available on the BBC website.
My first try is for the 'GoldFinger' drama.  The pid for this is
http://www.bbc.co.uk/programmes/b00rq1w3 and I've renamed the
programme 'Saturday_Drama-Goldfinger.m4a'

When I use get_player --tagonly --pid
http://www.bbc.co.uk/programmes/b00rq1w3 I get the following:

get_iplayer --tagonly --pid http://www.bbc.co.uk/programmes/b00rq1w3
INFO: Episode-only pid detected
INFO: Trying pid: b00rq1w3 using type: tv
INFO: Trying to stream pid using type tv
INFO: pid not found in tv cache
Matches:
WARNING: The 'default' programme version could not be determined
WARNING: No programme versions found
WARNING: You may receive this message if you are using get_iplayer
outside the UK
INFO: No versions of this programme were selected (available versions: )
INFO: File name prefix = Satuday_Drama-Goldfinger

INFO: 1 Matching Programmes
WARNING: The 'default' programme version could not be determined
WARNING: No programme versions found
WARNING: You may receive this message if you are using get_iplayer
outside the UK
ERROR: Failed to get version pd metadata from iplayer site

INFO: Episode-only pid detected
INFO: Trying pid: b00rq1w3 using type: radio
INFO: Trying to stream pid using type radio
INFO: pid not found in radio cache
Matches:
WARNING: The 'default' programme version could not be determined
WARNING: No programme versions found
WARNING: You may receive this message if you are using get_iplayer
outside the UK
INFO: No versions of this programme were selected (available versions: )
INFO: File name prefix = Satuday_Drama-Goldfinger

INFO: 1 Matching Programmes
WARNING: The 'default' programme version could not be determined
WARNING: No programme versions found
WARNING: You may receive this message if you are using get_iplayer
outside the UK
ERROR: Failed to get version pid metadata from iplayer site

However, I can download the metadata into an XML file with:

get_iplayer --metadata-only --metadata generic --pid
http://www.bbc.co.uk/programmes/b00rq1w3

Am I missing something obvious here?

Thanks,
Jimmy