Found 19th Aug 2014
FREE parking for two hours in the Long Stay Car Park at Heathrow Terminal 4. Easy free shuttle bus transfer to Terminal 4 which runs every 10 minutes. Transfer time is about 3 minutes. This is the official Heathrow Terminal 4 Long Stay Car Park. The sign on entry to the car park confirms that there is no charge for up to 2 hours. The free shuttle bus return is from bus stop 3 directly outside the terminal 4 door. The free parking is for drop off and pick up and free entry is not permitted in the same vehicle within 24 hours. You will pay £10 for between 1 & 2 hour parking in the short stay car park, but PLEASE NOTE if you go over your free 2 hours you will be charged the daily rate of £25! Found it by accident and saved myself £10 when picking up my nephew from his flight. I arrived 45 minutes before his flight landed and still had time to get back with a comfortable 20 minutes to spare.