VBA Code to convert Postcode in to OS grid co-ordinates

OSgridPcode.bas

Sub OSgridPcode()
'Converts postcode into OS x,y
'www.childs.be
'
    Dim sURL As String, sHTML As String
    Dim oHttp As Object
    miles = 6.21371192237334E-04
    cellr = ActiveCell.Row
    cellc = ActiveCell.Column
    Do While Cells(cellr, cellc - 1) <> ""
        sURL = "http://streetmap.co.uk/postcode/" + ActiveSheet.Cells(cellr, cellc - 1).Value
        On Error Resume Next
        Set oHttp = CreateObject("MSXML2.XMLHTTP")
        If Err.Number <> 0 Then
            Set oHttp = CreateObject("MSXML.XMLHTTPRequest")
            MsgBox "Error 0 has occured while creating a MSXML.XMLHTTPRequest object"
        End If
        If oHttp Is Nothing Then
            MsgBox "For some reason I wasn't able to make a MSXML2.XMLHTTP object"
        Exit Sub
        End If
        oHttp.Open "GET", sURL, False
        oHttp.Send
        sHTML = oHttp.responseText
        coordx1 = InStr(1, sHTML, "SM_locationX", vbTextCompare)
        coordx2 = InStr(coordx1, sHTML, ";", vbTextCompare)
        coordy1 = InStr(1, sHTML, "SM_locationY", vbTextCompare)
        coordy2 = InStr(coordy1, sHTML, ";", vbTextCompare)
        coordx = Mid(sHTML, coordx1 + 15, coordx2 - coordx1 - 15)
        coordy = Mid(sHTML, coordy1 + 15, coordy2 - coordy1 - 15)
        Cells(cellr, cellc).Value = coordx * miles
        Cells(cellr, cellc + 1).Value = coordy * miles
        cellr = cellr + 1
    Loop
End Sub