The House of Commons is an odd institution. One MP described it to me as very similar to a public school. I wouldn't have any idea about that, but it is true that nobody tells you the rules until you break them.

It is commonly thought that there are rules about what MPs can wear. I have written in this column before about wearing a suit, but last week I thought I would test what the rules really were in Business Questions. I didn't expect my tongue in cheek suggestion of a ‘dress down Thursday' in the Commons to attract so much attention.

But I was even more surprised to hear Robin Cook, the Leader of the House, say that there was no official dress code for MPs. The Speaker soon changed that when I tried it out, and said he prefers jackets and ties.

There are also rules for some officers of the House. The Speaker told me last week how he gets criticized by scruffily dressed journalists for not wearing knee breaches and silk stockings. But officers like ‘Black Rod', who was recently in the news over the arrangements for the Queen Mother's funeral, still dresses in medieval garb.

It is also commonly thought by MPs that music is not permitted in the Houses of Parliament. One MP told me that this was because it is still a royal palace and only the Queen's musicians can play there. After the recent Buckingham Palace concert I presume that includes Ozzy Osbourne!

I attended a meeting in Parliament this week with music industry representatives, including Mick Hucknall of Simply Red. I thought I would check up on the music rule.

It turns out it is possible to have live music in the House providing that you get permission from another costumed official, the Sergeant at Arms, who also wears silk stockings, and carries a sword around with him.

He can't be too bad, because he recently gave permission to my colleague David Lammy, the MP for Tottenham, allowing the excellent soul singer Alicia Keys to perform for young people in a Commons committee room.

It is also said that MPs are not allowed to die in the Palace of Westminster! This again is supposed to be because of its royal status. On the rare occasions when MPs expire on the premises, it is always reported that they died at St. Thomas' Hospital, across the river.

Neither do the normal laws of the land apply in the Palace of Westminster. Certainly Health and Safety rules appear not to apply. The Members' Tea Room is suffering from a plague of mice at the moment, which has led to some MPs suggesting that the House authorities should acquire a cat.

Aneurin Bevan once got into hot water for saying that in his opinion, the Tories were ‘lower than vermin.' One particularly bold rodent seems so at home down their end of the Tea Room that he has now been christened the ‘Mouse of Commons.'

Somehow though, despite all the unspoken rules and the lack of regulation, Parliament gets on with its job of making the rules for the rest of society, where a restaurant infected with mice would face instant closure, and a man wearing black silk stockings and carrying a sword would probably face instant arrest.