Charlotte Owen was nominated to parliament's upper chamber by Mr Johnson following his resignation as prime minister last year.

The adviser will now be known as Baroness Owen of Alderley Edge and sit as a Conservative peer.

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She joins another Johnson ally, Ross Kempsell - now Lord Kempsell - in entering the Lords. He joined the House last week at the age of 31.

In a scathing report released last week, the committee which advises the House of Lords on ways to reduce its membership criticised Mr Johnson for the number of people he ennobled.

The Lord Speaker's committee on the size of the House highlighted Mr Johnson as showing "no interest" in trying to reduce the number of peers.

According to a biography issued by the House of Lords, Lady Owen graduated from the University of York in 2015, before going on to work as an adviser to Conservative MPs Sir Alok Sharma, Mr Johnson, and Sir Jake Berry.

She also worked for Mr Johnson in Downing Street, as well as Liz Truss. Lady Owen also worked for Chris Heaton-Harris when he was chief whip in early 2022.

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Lord Kempsell was previously a political director of the Conservative Party and has also worked closely alongside Mr Johnson for several years.

The Tory mayor of the Tees Valley Combined Authority, 36-year-old Ben Houchen, joined the Lords alongside Lady Owen.

Shaun Bailey - now Lord Bailey - joined the upper chamber last week. There had been criticism of his peerage as his staff took part in a lockdown-breaking Christmas party at Conservative Party headquarters in December 2020.

The Lords in 2017 set an aim to reduce the number of peers to around 600 - but it remains above 800.

Last week's report noted that "progress" was being made to shrink the House until Mr Johnson took over and increased the number of appointments.

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He drew criticism on numerous occasions for his approach to the Lords, including appointing Lord Lebedev, the son of a former KGB agent, and Lord Cruddas, a Tory donor, despite being told by the House of Lords Appointments Commission (Holac) it could not support giving him a seat.

More than half of Mr Johnson's peerage nominations were not accepted by Holac - including Nadine Dorries and Nigel Adams.