Regex parameters
^([A-PR-UWYZ0-9][A-HK-Y0-9][AEHMNPRTVXY0-9]?[ABEHMNPRVWXY0-9]? {1,2}[0-9][ABD-HJLN-UW-Z]{2}|GIR 0AA)$
/^([Oo][Xx][AEHMNPRTVXY0-9]?[ABEHMNPRVWXY0-9]? {1,2}[0-9][ABD-HJLN-UW-Z]{2}|GIR 0AA)$/
/^([Oo][Xx]$/
(OX2|OX1|OX3)
/(OX2|OX1|OX3)/
CV36,CV47,HP18,HP19,HP22,MK11,MK12,MK13,MK18,MK19,MK77,MK8,NN11,NN12,NN13,OX1,OX15,OX16,OX17,OX18,OX2,OX20,OX25,OX26,OX27,OX28,OX29,OX3,OX33,OX4,OX44,OX5,OX6,OX7,OX8,OX9
/(CV36|CV47|HP18|HP19|HP22|MK11|MK12|MK13|MK18|MK19|MK77|MK8|NN11|NN12|NN13|OX1|OX15|OX16|OX17|OX18|OX2|OX20|OX25|OX26|OX27|OX28|OX29|OX3|OX33|OX4|OX44|OX5|OX6|OX7|OX8|OX9)/
http://www.freemaptools.com/find-uk-postcodes-inside-radius.htm – above postcodes from 20 mile radius from home
regex links
http://www.cheatography.com/davechild/cheat-sheets/regular-expressions/
http://www.regexr.com
