How to download subtitles when episode is not in cache

[Timothy]

Hello,
I noticed that if a program is not in the TV cache, the subtitles won't 
download. My usual command for getting subtitles is:
get_iplayer --modes=subtitles --subtitles-only --pid <pid>

Using the --verbose switch however, I see that subs are actually available.

Is there a workaround for this? Getting the video is fine whether or not a 
program is in the cache.

Have a great week,
Timothy