function validate_form_event(thisform) {
  if (!validate_standard_fields(thisform)) { return false; }
  }

function validate_standard_fields(thisform) {
  with (thisform) {
    if ( first_name.value.length < 2 ) {
     alert('Please enter your full name.');
     first_name.focus();
     return false;
     }
    if ( surname.value.length < 2 ) {
     alert('Please enter your full name.');
     surname.focus();
     return false;
     }
    if ( address.value.length < 15 ) {
     alert('Please enter your full address.');
     address.focus();
     return false;
     }
    if ( postcode.value.length < 6 ) {
     alert('Please enter your full postcode.');
     postcode.focus();
     return false;
     }
    }
  return true;
  }