repeating your address 3 times with postcode PA23 6NH, PA2 6NH and PA2Q 6NH as test for you pattern and using the regex from wikipedia against yours, the code is..
import re
s="123 Some Road Name
Town, City
County
PA23 6NH
123 Some Road Name
Town, City"
"County
PA2 6NH
123 Some Road Name
Town, City
County
PA2Q 6NH"
#custom
print re.findall(r'[A-Z]{1,2}[0-9][A-Z0-9]? [0-9][ABD-HJLNP-UW-Z]{2}', s)
#regex from #http://en.wikipedia.orgwikiUK_postcodes#Validation
print re.findall(r'[A-Z]{1,2}[0-9R][0-9A-Z]? [0-9][A-Z]{2}', s)
the result is
['PA23 6NH', 'PA2 6NH', 'PA2Q 6NH']
['PA23 6NH', 'PA2 6NH', 'PA2Q 6NH']
both the regex's give the same result.
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