The booked haulage is 47580 'County of Essex'.
http://retrorailtours.co.uk/rt5.php
The normal price is £55, but this is reduced to £49.50 to anyone who books before the end of this month. If you send me a PM on this forum by the end of this month, you will also get a voucher to collect a free cup of tea/coffee from the buffet car on train