I got the answer - posted below!
Code
Sub MG16Nov23()
Dim Rng As Range, Dn As Range, R As Range, c As Long, Num As Double
Set Rng = Range("A1", Range("A" & Rows.Count).End(xlUp)).SpecialCells(xlCellTypeBlanks)
For Each Dn In Rng.Areas
c = 0
For Each R In Dn
c = c + 1
R.NumberFormat = "hh:mm:ss"
R.Value = DateAdd("s", c, Dn(1).Offset(-1))
Num = ((Dn(1).Offset(-1, 1) - Dn(Dn.Count).Offset(1, 1)) / (Dn.Count + 1))
R.Offset(, 1).NumberFormat = "0.0"
R.Offset(, 1).Value = Dn(1).Offset(-1, 1) - Num * c
Next R
Next Dn
End Sub
Display More
Thanks to MickG from MrExcel.com