Michael Portillo continues his 300-mile Scottish coastal journey along the Firth of Forth at the railway engineering icon for which it is famous throughout the world — the Forth Bridge. A highlight for rail travellers, Michael remembers his delight in the crossing as a child visiting his Scottish grandparents. On the firth's southern bank, Michael stops in the port of Leith to tour the Royal Yacht Britannia. Now decommissioned, she is moored as an attraction. Michael is fascinated to hear how guests were entertained on board and is happy to recall an experience of his own concerning the fate of the world-famous vessel. Heading west along the coast to Bo'ness, Michael savours the smuts puffing from the chimney of the Caledonian Blue locomotive belonging to the heritage Bo'ness and Kinneil Railway. The enthusiasm of the volunteers who run the line is infectious. The next stop is in the Forth Valley close to Falkirk, where the Forth and Clyde Canal meets the River Carron and two 300-tonne steel sculptures tower over a vast eco-park. Michael is introduced to the Kelpies, Duke and Baron, by their creator, sculptor Andy Scott, who joins him on a video call from the United States. Michael crosses the River Forth at Stirling, heading east to Alloa on the northern bank. One of Scotland's oldest industries continues here today — glass manufacture. Michael tours a vast bottle-making plant staffed by generation upon generation of glass workers in a 270-year-old factory. Travelling downstream to Culross, Michael discovers the railway — now freight only — runs along the waterfront because coastal strips of land such as this were flat and therefore relatively cheap. It cut the village from its foreshore. In Culross, Michael discovers a wonderfully preserved palace and recreated 16th-century garden.