After Starmer's announcement on resignation, how is his successor chosen? (opens original article in a new tab)

Prime Minister Keir Starmer announced his resignation, with a new leader to be in place by September, leading to Britain's seventh leader in 10 years.

• Prime Minister Keir Starmer announced his resignation.
• A new leader will be in place by September when parliament returns.
• This would make Britain's seventh leader in 10 years.