In a surprise move, Jeremy Corbyn has been revealed as the keynote speaker at this weekend’s Progress Conference. The Labour leader is not seen as a natural ideological ally of the group, which last year endorsed a vote for “anyone but Corbyn” in the leadership contest.

The speech, a last minute reveal ahead of the conference tomorrow, will be seen as an attempted olive branch between the two wings of the party, although it is not yet clear what kind of address Corbyn will deliver.

Progress has traditionally been associated with the politics of Tony Blair, and hosted an intervention by the former Prime Minister during the leadership election last year where he warned against voting for Corbyn.

In a Progress magazine editorial published last summer, the organisation supported Labour members using all three votes on their leadership ballot to diminish the chances of Corbyn winning. Endorsing Liz Kendall, the leader column said: “Kendall is the first, right and heartfelt choice. You pick the remaining order but do not fail to cast both two and three for anyone but Corbyn.”

Those from Corbyn’s wing of the party have not always been particularly warm towards Progress either. Jon Lansman, chair of Momentum, wrote in 2011 that Progress was a “Blairite party-within-the-party”, while Shadow Chancellor John McDonnell described the group as being “hard right” and having a “conservative agenda”.