function checkUKTelephone (telephoneNumber) {

  // Convert into a string and check that we were provided with something
  var telnum = telephoneNumber + " ";
  if (telnum.length == 1)  {
     telNumberErrorNo = 1;
     return false
  }
  telnum.length = telnum.length - 1;
  
  // Don't allow country codes to be included (assumes a leading "+")
  var exp = /^(\+)[\s]*(.*)$/;
  if (exp.test(telnum) == true) {
     telNumberErrorNo = 2;
     return false;
  }
  
  // Remove spaces from the telephone number to help validation
  while (telnum.indexOf(" ")!= -1)  {
    telnum = telnum.slice (0,telnum.indexOf(" ")) + telnum.slice (telnum.indexOf(" ")+1)
  }
  
  // Remove hyphens from the telephone number to help validation
  while (telnum.indexOf("-")!= -1)  {
    telnum = telnum.slice (0,telnum.indexOf("-")) + telnum.slice (telnum.indexOf("-")+1)
  }  
  
  // Now check that all the characters are digits
  exp = /^[0-9]{10,11}$/
  if (exp.test(telnum) != true) {
     telNumberErrorNo = 3;
     return false;
  }
  
  // Now check that the first digit is 0
  exp = /^0[0-9]{9,10}$/
  if (exp.test(telnum) != true) {
     telNumberErrorNo = 4;
     return false;
  }
  
  // Finally check that the telephone number is appropriate.
  exp = /^(01|02|03|05|070|077|07624|078|079)[0-9]+$/;
  if (exp.test(telnum) != true) {
     telNumberErrorNo = 5;
     return false;
  }
  
  // Telephone number seems to be valid - return the stripped telehone number  
  return telnum;
}
var telNumberErrorNo = 0;
var telNumberErrors = new Array ();
telNumberErrors[0] = "Valid UK telephone number";
telNumberErrors[1] = "Telephone number not provided";
telNumberErrors[2] = "UK telephone number without the country code, please";
telNumberErrors[3] = "UK telephone numbers should contain 10 or 11 digits";
telNumberErrors[4] = "The telephone number should start with a 0";
telNumberErrors[5] = "The telephone number is either invalid or inappropriate";

  
  function checkForm() {
  name = document.getElementById("name").value;
  email = document.getElementById("email").value;
  telephone = document.getElementById("telephone").value;
  comments = document.getElementById("comments").value;

var filter=/^([\w-]+(?:\.[\w-]+)*)@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$/i

  if (name == "") {
  hideAllErrors();
document.getElementById("nameError").style.display = "inline";
document.getElementById("name").style.background = "#FFFFFF";
document.getElementById("name").select();
document.getElementById("name").focus();
  return false;
  } else if (email == "") {
hideAllErrors();
document.getElementById("email").style.background = "#FFFFFF";
document.getElementById("name").style.background = "#EFF3FA";
document.getElementById("emailError").style.display = "inline";
document.getElementById("email").select();
document.getElementById("email").focus();
  return false;
  } else if (!filter.test(email)) {
hideAllErrors();
document.getElementById("name").style.background = "#EFF3FA";
document.getElementById("emailError2").style.display = "inline";
document.getElementById("email").select();
document.getElementById("email").focus();
  return false;
  } else if (telephone.length > 0) {
	 if (!checkUKTelephone (telephone)) {
hideAllErrors();
document.getElementById("telephone").style.background = "#FFFFFF";
document.getElementById("comments").style.background = "#EFF3FA";
document.getElementById("telError").style.display = "inline";
document.getElementById("telephone").select();
document.getElementById("telephone").focus();
return false;
  }
  }
  
if (comments == "") {
hideAllErrors();
document.getElementById("comments").style.background = "#FFFFFF";
document.getElementById("name").style.background = "#EFF3FA";
document.getElementById("email").style.background = "#EFF3FA";
document.getElementById("commentsError").style.display = "inline";
document.getElementById("comments").select();
document.getElementById("comments").focus();
  return false;
  }
  return true;
  }
 
  function hideAllErrors() {
document.getElementById("nameError").style.display = "none"
document.getElementById("emailError").style.display = "none"
document.getElementById("emailError2").style.display = "none"
document.getElementById("telError").style.display = "none"
document.getElementById("commentsError").style.display = "none"
  }