The House of Lords comprises of "about 800" unelected members (92 of them being hereditary peers, and 26 Anglican bishops). Lords with criminal records (regardless of hereditary, life peer or bishop) should be expelled from the House, and candidates with criminal records should not be considered.
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In 1999, the House of Lords Act reduced the number of hereditary peers to 92 from over 750. In 2015, further laws meant that any Lords convicted of serious criminal offences could be expelled - none have been.
While there are 800 unelected Lords, the Commons have only 650 MPs (who are elected). It is inappropriate for someone both unelected and with a criminal record to hold such an important position in the UK Parliament as Lords are involved in passing legislation, thus it must be banned.