From one gentlemen's club to another

Since Stuart times, convention has dictated that should any member of the Commons or the Lords be imprisoned, a notice must be read out in Parliament. This was to make sure that the King had not illegally detained someone in order to interfere with the proper functioning of democracy. And so, at 2.33pm on Tuesday afternoon:

The Lord Speaker (Baroness Hayman): My Lords, I have to inform the House that the Clerk of the Parliaments has received notification from the Ministry of Justice informing him that Lord Black of Crossharbour has been convicted of four offences at the United States District Court, Northern District of Illinois, and that the custodial sentence imposed by the court took effect yesterday.

The only exception is when the Member has been jailed for military offences, when the message has to come from the Queen. For a full list of Members who have been jailed since 1979, see here. For background details see "Report of the Select Committee on the Imprisonment of a Member" published in 1902.