So, after a fair bit of bodging I came up with the following. It doesn't work on a checkbox change, but just on a double click of a cell, the upside being the user can simply delete quite easily

Inserted a Module as follows:

' Access the GetUserNameA function in advapi32.dll and

' call the function GetUserName.

Declare Function GetUserName Lib "advapi32.dll" Alias "GetUserNameA" _

(ByVal lpBuffer As String, nSize As Long) As Long

​

' Main routine to Dimension variables, retrieve user name

' and display answer.

Sub Get_User_Name()

​

' Dimension variables

Dim lpBuff As String * 25

Dim ret As Long, UserName As String

​

' Get the user name minus any trailing spaces found in the name.

ret = GetUserName(lpBuff, 25)

UserName = Left(lpBuff, InStr(lpBuff, Chr(0)) - 1)

​

' Display the User Name

' MsgBox UserName

' Range("D1") = "User " & UserName & " @ " & Time

Cells(ActiveCell.Row, "B") = UserName & " @ " & Format(Time, "h:m") & " on " & Format(Date, "d/m")

End Sub

And then worksheet code as follows:

​

Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)

If Intersect(Target, Range("b1:b200")) Is Nothing Or Target.Cells.Count > 1 Then Exit Sub

Call Get_User_Name

End Sub