Yep M0.9/300kts this was identified as the cause of the loss of Hunter FGA MK9 FG 261 of 2 TWU from Lossiemouth in 28 May 1980 near Dufftown. 23 degrees of flap used for low speed ACM but if the flap is not selected up before M0.9/300kts is reached the nose will progressively pitch down and cannot be raised until the flaps are retracted.
UK Military Aircraft Losses