Clean and validate UK postcode

uk_postcode.php

<?php
  /**
   * Validate and parse UK post code
   *
   * @param string $postcode 
   * @return array(["validate"] => TRUE/FALSE
   *  ["prefix"] => first part of postcode
   *  ["suffix"] => second part of postcode);
   */
function inspect_postcode($postcode) {
   $postcode = str_replace(' ', '', $postcode); // remove any spaces;
   $postcode = strtoupper($postcode); // force to uppercase;
   $valid_postcode_exp = "/^(([A-PR-UW-Z]{1}[A-IK-Y]?)([0-9]?[A-HJKS-UW]?[ABEHMNPRVWXY]?|[0-9]?[0-9]?))\s?([0-9]{1}[ABD-HJLNP-UW-Z]{2})$/i";

   // set default output results (assuming invalid postcode):
   $output['validate'] = FALSE;
   $output['prefix'] = '';
   $output['suffix'] = '';

   if (preg_match($valid_postcode_exp, strtoupper($postcode))) {
     $output['validate'] = TRUE;
     $suffix = substr($postcode, -3);
     $prefix = str_replace($suffix, '', $postcode);
     $output['prefix'] = $prefix;
     $output['suffix'] = $suffix;
   }
   return $output;
  }
?>