What does BN stand for?

On Budget Night last month 93 BN's were issued by HMRC. It seems that most people assume that the BN annotation probably stands for 'Budget Note'. But are there more descriptive explanations?

Suggestions to date include:

• BaNal article
• Boring Note
• Barmy Notice
• Bloody Nuisance

If you have better suggestions please add them as comments on this post.