function validate_required(field,alerttxt)
{
with (field)
  {
  if (value==null||value=="")
    {
    alert(alerttxt);return false;
    }
  else
    {
    return true;
    }
  }
}

function validate_form(thisform)
{
with (thisform)
  {
  if (validate_required(name,"Please enter you name!")==false)
  {name.focus();return false;}
  }
   {
  if (validate_required(email,"Please enter you email!")==false)
  {email.focus();return false;}
  }
     {
  if (validate_required(number,"Please enter you telephone number!")==false)
  {number.focus();return false;}
  }
   {
  if (validate_required(postcode,"Please enter you Post code!")==false)
  {postcode.focus();return false;}
  }
}