Conservative Party chairman Grant Shapps has called on Ed Miliband to "come clean and publish Labour’s report into the Falkirk selection in full."
Mr Shapps added, "It’s clearer than ever that [Unite chief] Len McCluskey is calling the shots in the Labour Party."
More top news
The memorial service will be attended by Prince Harry and Meghan Markle.
David Browning admits manslaughter by diminished responsibility but denies murder.
Four people have died and the suspect is still at large, police said.