The A198 is the second-last A road to branch off the A1 (assuming you're coming from London, as the numbering scheme does). Shortly after the Dunbar roundabout at the north end of Dunbar, which the Scottish Office has insisted on naming the ``Beltonford Roundabout'' (no map I have ever seen has a Beltonford on it), the A1 has a sign off it pointing to the right towards North Berwick and points west.
This is the A198. There is a hill between the flat lands surrounding Haddington, and the valley of the Tyne, just to the north. This is the first challenge.
While the North Berwick to Haddington road, several miles further along the A1 culminates after about eight miles containing not fewer than 50 right-angled bends, the A198 is relatively straight if viewed on a map. On the surface, however, getting from the A1 to Tyninghame is a bit like going to Alton Towers. Tyninghame itself is a tiny village in a wood and unworthy of further mention.
After a few bends, however, we come to Whitekirk . There's a row of formerly-local-authority housing for farm workers, then a T-junction just to the south of the kirk, which is made of red sandstone. I can't remember why Whitekirk is so-called. Taking the spur to the left takes you into deepest East Lothian, but taking the A198 to the right leads to a splendid coastal stretch.
Then a magnificent stretch of wheat-when-I-last-looked-probably-rape-now, three right-angled bends in the space of a mile, and Tantallon Castle on your right. It's a magnificent red sandstone castle, with carpark full of tourist buses, but currently rather horrifically ruined.
Just to the north is the Bass Rock, which has a gannet sanctuary, puffins, guillemots, and a lighthouse. A Mr Marr of North Berwick runs boat trips to it in his boat ``Sula II'', owing to the lack of fish in the North Sea these days.
Be sure to turn left and continue along the A198 here, otherwise you'll find yourself embedded in the farm at Auldhame. Now travelling to the west the view consists of the Law Brae, oddly like a whale when seen side-on, the coastal town of North Berwick, then in the sea, Fidra, the Lamb and Craigleith, the Kingdom of Fife just across the water, and in the distance, Arthur's Seat and the Forth bridges.
Passing the ludicrously-sited out-of-town council estate ``Limegrove'' on your right, then the small caravan site which reaches Jacob's Ladder (now running up the side of a brand new sewage pumping station), a former lemonade factory on your left, and, also on your left, the Ben Sayers factory (where they make and sell golf clubs), we reach the roundabout at the bottom of the Heugh .
Straight ahead of you is Prestos. Neil Simpson used to work there. North Berwick is mostly a grid, and I'm not entirely sure about what route to take through the middle, but eventually you get to Dirleton Avenue. This is full of big Victorian houses built in the days when the quality had maids.
Now the quality don't have maids and the houses have been subdivided into flats. Dirleton Avenue is straight and runs on to the Dirleton bypass. On your left is a filling station. There used to be one at the end of Quality St called the Dalrymple garage (named after the Hamilton-Dalrymples who own most of East Lothian), but it doesn't produce petrol anymore.
The land surrounding you is flat and mostly agricultural. Dirleton is on a wee hill, and has a touristy castle in rather better repair than Tantallon. Otherwise, it's a quite pretty standard village, with village green and local authority housing for farm labourers. There's a wee bit of commuter element.
Gullane comes after Dirleton, and hasn't been bypassed. Here we have a fire-training school, Muirfield golf course, where Caroline used to work, and Ronnie Corbett's house. The golf course straddles the A198 at the far end of Gullane. This isn't as much fun as you might imagine.
More bends in the road take you to a huge bay. Aberlady Bay, in fact, which a number of folk claim has the biggest difference between high tide and low tide in Scotland/the UK/Europe/the world. Aberlady has another filling station on the right hand side of the road, and a number of rather pretty old houses.
Now we come into the wooded bit before the coalfields. We carry on along the coast, skirting the woods, until we are plunged into Longniddry. Longniddry is a dormitory town for Edinburgh, but as this development all came a long time after the Education Act, it doesn't have a high school as towns of similar size (North Berwick, Dunbar, Tranent, Prestonpans) do.
After negotiating the roundabout with the B1377 (correct me if I'm wrong), a road with possibly the worst roundabout in the world on it, we come to possibly the least-enforced speed limit in the world. But-nobody has an average speed of less than 30mph between the corner shop and the dual carriageway, in either direction.
There's two advertising hoardings by the roundabout, just outside the railway station, put up in the vain hope that some drivers go slowly enough to read them.
The dual carriageway runs alongside the Intercity East Coast line, which has led to more than one fatal accident when folk try to race the 125. On your left is a motel which closed down many years ago. In 1995 the last ripped remaining trace of flag (Israeli, weirdly enough), blew off one of the five flagpoles on top of it.
Cosmic Coachcraft, a car recovery firm, is on your right. Then we come to Prestonpans. Here you can either turn to your left onto the A1 (A720 Edinburgh bypass), or go through Prestonpans, site of a few factories, and a famous battle involving Jacobites.
Next Port Seton, a fishing port which is being repeatedly whacked by EU fishing policy, and Cockenzie power station, which is coal-fired and run by Scottish Power. They used to get the coal from the nearby opencast mine. God knows where they get it from now.
Shortly after this we hit Musselburgh. This is in Midlothian. The High Street used to be chock full of traffic before they built the A720, but now it's relatively civilised. The best ice-cream in Lothian Region (featured in Trainspotting) is on Musselburgh High Street. My dad used to work in the Royal Bank next door.
Musselburgh, on the Esk, gets rather less picturesque when you cross the bridge (there's actually a fair bit of Esk about in Musselburgh - a few years back someone drowned), we pass lots of shops, the Brunton  Theatre on the right, a Shell filling station on the right (one of my earliest memories), and soon we hit the A1 for real.