As per: http://aa.net.uk/news-2012-09-bh.html
We are pleased to announce that from today all bank holidays and public holidays will be treated in the same way as evenings and weekends for all of our broadband line customers. This means that the usage rate on these days will be metered at 50GB per unit.
We are proud to be an ISP that listens to our customers, and that makes changes in line with their suggestions if it is possible for us to do so. In this case, taking into account the 154 votes from our ideas site, and also feedback we received from customers after the Royal Wedding and the Queen's Diamond Jubilee, we have made this change today.
Looking forward, although there are no huge national events in the near future, we hope customers will find it useful for watching streamed television or movies on demand, or doing those data-heavy operating system updates, on their days off.
Notes
This will only apply to broadband line usage, not VoIP, or L2TP, or mobile or anything else. Public and bank holidays are different in Scotland and Northern Ireland, so we use the line postcode to work out which applies. The first example will be 30th Nov for St Andrew's day relating only to Scottish lines.