UK postal code flat pattern matching regular expression

UK postal code flat pattern matching regular expression:

Patterns:

A9 9AA

A99 9AA

A9A 9AA

AA9 9AA

AA99 9AA

AA9A 9AA

Note:  

A indicate alphabets from A to Z.

9 indicate number from 0 to 9.

Regular Expression = “^(((([A-Za-z][0-9]{1,2})|(([A-Za-z][A-Za-z][0-9]{1,2})|(([A-Za-z][0-9][A-Za-z])|([A-Za-z][A-Za-z][0-9]?[A-Za-z])))) [0-9][A-Za-z]{2}))$”

Hope this will help other who wants only pattern matching expression.