The Green Party leader launched his bid to be a candidate in the Holborn and St Pancras contest on Thursday morning.

The decision to stand in the seat could be a major headache for Andy Burnham in what will be his first electoral test as Prime Minister.

Speaking to the the constituency’s local paper, the Camden New Journal, Mr Polanski said: โ€œI have lived and worked in this community over many years, I know it well and I love it.

โ€œIt represents so many of the things that make London so special. I am so excited by the prospect of representing this place in Parliament.โ€

โ€œHolborn and St Pancras has everything thatโ€™s the best of our country and so much potential.”

He added: โ€œBut for too long now itโ€™s been held back by governments who have failed to make the changes to improve peopleโ€™s lives.

โ€œWe know that the Greens can win here, and by electing me, voters will have someone who will always fight their corner โ€“ never scared of big donors or the party whip. Too often Labour has stood up for corporations and big money. I will stand up for people struggling to pay their bills.โ€

Former Prime Minister Sir Keir, who announced his intention to quit as an MP earlier this week, plans to focus on international affairs.

His closest challenger in the constituency at the 2024 general election was the independent candidate Andrew Feinstein.

Mr Polanski still needs to be officially selected by local Green members.

The Party have won council seats in London and overall control of other boroughs but they have never won a parliamentary seat in the capital.

This will be a huge test for Mr Polanski, whose popularity has diminished slightly in recent months.

The Green Party has also been marred by internal splits and factional infighting.