Licence to Thrill

There won't be any thrilling with this blip. Completely forgot, then couldn't be bothered finding anything good, so picked up my mail and phone.

My TV Licence was automatically renewed today, but no part credit for this week even though I've only had TV on about three times, for less than an hour at a time.

Does anyone know why the TV Licence is paid 6 months in arrears and 6 months in advance if paying direct debit?