Keir Starmer’s speechwriter and close aide Chris Ward has told colleagues he is leaving his post after six years, in the latest departure from the Labour leader’s top team. Ward has been Starmer’s deputy chief of staff since he won the Labour leadership last year, but has worked at Starmer’s side since 2015, writing his speeches and helping to prepare him for appearances at prime minister’s questions. He was one of a close-knit group of senior advisers around Starmer known as the “gang of five” by backbench MPs. Of the five, only policy chief Claire Ainsley remains in post after a radical shake-up kicked off in the wake of the Hartlepool byelection defeat. Former director of communications Ben Nunn has left, political secretary Lady Jenny Chapman has become a frontbench spokesperson, and Morgan McSweeney will move to be elections chief. Ward was closely involved in Starmer’s leadership bid, and had previously worked with him when Starmer was shadow Brexit secretary in Jeremy Corbyn’s frontbench team, including on the ill-fated Brexit talks with Theresa May’s government. It is understood Ward discussed his departure with Starmer earlier this week, in what friends said was an “emotional” conversation. Starmer said: “Chris has worked with me for six years and has been brilliant throughout. I am very sad to see him go and hope that we will work together again at some point in the future.” Ward’s departure will raise the question of who will write Starmer’s crucial speech for Labour’s conference in Brighton in September – the first he will have been able to deliver to a live audience. Starmer has faced questions from colleagues about his vision for the country as the pandemic abates, and the speech – which will follow a summer tour of the UK where he will meet voters – will be analysed intently. In a message to colleagues seen by the Guardian, Ward said: “When I first met Keir in October 2015 it was as clear to me then, as it is now, that he will be a superb prime minister and leader of the Labour party. To be able to play a role in that journey has been an enormous privilege.” Starmer’s new chief of staff Sam White, a former adviser to the former Labour chancellor Alistair Darling, is due to arrive in post next month. The Labour leader has made a string of other new appointments in recent weeks. Several of these, including acting director of communications Matthew Doyle, are veterans of the Blair years, raising questions on the left of the party about the direction of Starmer’s political project. However, some of those concerns have been assuaged in recent days by the announcement of several radical labour market policies by Starmer’s deputy, Angela Rayner, including the creation of a single class of worker, allowing all staff employment rights from day one of their job.