Help speeding up a loop

Hi All

The following loop that loops through and generates all possible postcodes in the UK.

How can I change the attached code so that the outer part of each loop is not repeated?

Ie.

The loop has 4 parts...

The outer loop goes through a list of districts....
             
     The Next part generates (1) 1 Digit
         The inner part will Generate 1 Digit followed by 2 Characters

     The Next part generates (2) 2 Digits
         The inner part will Generate 1 Digit followed by 2 Characters

     The Next part generates (3) 1 Digit & 1 Character
         The inner part will Generate 1 Digit followed by 2 Characters


How would I remove the repeating outer part from each loop?

So that I would only require 1 loop that does something along the lines of

The outer loop goes through a list of districts....
             The Next part generates (1) 1 Digit
             The Next part generates (2) 2 Digits
             The Next part generates (3) 1 Digit & 1 Character
                          The inner will Generate 1 Digit followed by 2 Characters

The main thing is though I still have to be able to have each loop outputing the format like so

Distric    1 Digit     1 Digit & 2 Characters
Distric    2 Digit     1 Digit & 2 Characters
Distric    1 Digit & 1 Character     1 Digit & 2 Characters

Any help would be great

many thanks
Steve

For Each r1 As String In District
            s1 = r1
 
            For Each r2 As String In Digit1
                s2 = s1 & r2 & " "
                For Each r3 As String In Digit1
                    s3 = s2 & r3
                    For Each r4 As String In Alpha2
                             '......do stuff
                    Next
                Next
            Next
 
            'Pass 2
            For Each r2 As String In Digit2
                s2 = s1 & r2 & " "
                For Each r3 As String In Digit1
                    s3 = s2 & r3
                    For Each r4 As String In Alpha2
                             '......do stuff
                    Next
                Next
            Next
 
            'Pass 3
            For Each r2 As String In Digit1
                s2 = s1 & r2
                For Each r3 As String In Alpha1
                    s3 = s1 & s2 & r3 & " "
                    For Each r4 As String In Digit1
                        s4 = s3 & r4
                        For Each r5 As String In Alpha2
                             '......do stuff
                        Next
                    Next
                Next
            Next
        Next

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