Michael Portillo's rail exploration of the eastern reaches of England is drawing to a close. His travels today begin on the smallest public railway in the world, the Wells and Walsingham line. This narrow-gauge heritage service takes him through the heart of the glorious north Norfolk countryside and delivers him to Wells-Next-the-Sea, from where he heads to the magnificent Holkham Hall. From Watlington, Michael makes his way to one of the largest seal rehabilitation centres in the country, run by the RSPCA at East Winch. Meanwhile, the historic town of King's Lynn with its port on the River Ouse has enjoyed a proud maritime past and its beautifully preserved centre impresses Michael. At first light, Michael arrives on the Wash at Snettisham amid a stunning landscape of sandbanks, salt marshes and lagoons, where the RSPB manages a nature reserve. Michael joins the site manager and other twitchers to witness a spectacular natural event.