"Did you remember to bring it?" asks Sarah. I check again to make sure it's still there. The silver brooch in my pocket feels warm in my hand. A light drizzle is falling as we wait on the platform. Water drips from a broken gutter on the front of the passenger shelter. Sarah is humming quietly to herself, a cheerful nameless tune. She often hums when she's happy. We stand reading the notice-board. Apart from Sarah and myself, the little platform, that is Llangadog station, is deserted. We watch as the train slowly approaches along the single track. I call it a train but really it's just one old, tired, carriage. Behind us a claxon sounds as the level crossing closes. I look at my watch. The train's early.
The guard opens a door and steps on to the platform. He's smiling. "Bore da, good morning."
We answer and climb aboard. I know Sarah prefers to travel looking forward and choose seats facing a table. There are three other passengers on the train, a man in his sixties, balding and overweight, a younger woman reading a book and, at the far end of the carriage, a tall thin man dressed as if he's about to climb Everest.
"Did you lock the car?" asks Sarah. She knows I forget to lock doors. Last year we were five miles from home when she asked and I couldn't remember. She made me turn around and drive back to find the front door wide open.
"Yes," I reply, more sharply than I intend. "You watched me lock it and you tried the handle."
The carriage is hot and stuffy. I unzip my jacket and squeeze into the seat. The diesel engine rumbles and we start to move.
"Tickets please?" The guard inspects our bus passes.
It was Sarah who discovered we could use the bus passes and travel for free on the train.
"Shrewsbury, for the day?" asks the guard.
"Yes," says Sarah. We go past cars queuing at the crossing. The train gathers speed, "Clickety-clack, clickety-clack."
It stops raining. A glimpse of blue, enough to patch a sailor's trousers, appears. The sun is, probing, searching for a gap, looking for a way through the clouds.
We're in the country now, rattling past lush green fields, cows and sheep. There's a different sound, a hollow rumble, as the train crosses the Towy. The water level in the river is high close to breaking its banks, of flooding the meadows and fields.
"Llanwrda," shouts the guard. The train slows and stops.
School children get on, filling the carriage with noise; an excited babble of conversation and laughter. The balding man pulls a face and hides behind his newspaper.
We are past Llandovery. The carriage is quiet now the children have gone, an adult world of polite personal space, reading and day dreaming. The tall thin man summons the guard and points to his phone. "The wi-fi isn't working." He looks cross.
"It's broken," says the guard and shrugs.
Sarah pours coffee from a flask. We sip the hot liquid as the train trundles across Cynghordy Viaduct.
The train continues on along the single track. Branches brush against the windows spilling dappled sunlight into the carriage.
The train is slower now. Outside all is dark. The noise of the engine is deafening. I can taste burnt diesel fumes. We are in a tunnel climbing towards the Sugar Loaf. Light floods the carriage as we emerge from the gloom.
"The Heart of Wales," Says Sarah.
We admire the view. Miles of verdant farmland, woods and heath lay before us - a colossal tapestry of shapes and colours. A red kite is circling effortlessly above. I watch a farmer, on a quad bike, drive sheep in the distance.
The train stops at Llanwrtyd. "We'll be here about ten minutes," announces the guard, "waiting for the train from Shrewsbury. You can get out and stretch your legs. Don't worry we won't go without you."
"Come on," says Sarah. "And don't forget your stick."
We explore the station. There's a smell of fresh paint. Women, planting flowers in a raised bed, are laughing at something. The beds are a riot of red geraniums, blue larkspur and yellow flowers whose name I do not know. A southbound train appears and stops alongside our carriage. Our driver and guard cross the track. This is as far as they come.
"We'd better get back," says Sarah.
A woman hurries along the platform. With her are three children. She follows us onto the train, scans the carriage and comes towards us. "Do you mind?" she says and points. "The table, we want to play cards." She expects us to move?
"Yes we do mind," says Sarah and looks at me. "Some people, really."
The woman glares and moves to some seats behind us. As she goes by she knocks my walking stick over.
"Bloody thing," she mutters as she picks it up.
"Tickets. Have your tickets ready," shouts the guard. It's a different man. He moves quickly through the carriage, checking we've all paid, hoping to catch a dodger, efficient; a jobs-worth.
We are in Knighton, 'Tref-y-Clawdd', the town on the Dyke. Our train crosses the border. There are no border guards, no passport checks. Offa's kingdom lies ahead. The Pillar of Eliseg, with the stonemason's typo, explains all. Welsh mountains give way to the farmlands of England.
"Can we start with the castle? It isn't far. I should be able to walk if we go slowly," I say as we leave Shrewsbury station.
"Then we'll have lunch," says Sarah. She knows the regimental museum is there. She knows I want to see the medal.
The curator, an old man dressed in sports jacket and grey trousers is wearing a regimental tie. The immaculate knot, the fresh creases in his trousers and his upright bearing says it all; he was an officer. He leads us through exhibits with a steady commentary. He speaks confidently, with pride choosing his words with care. "Princess Margaret came here once. I showed her around." He pauses in the great hall to point out the Mess Silver, fabulous cups and plates in a glass display case. "She asked me for a fag. Not what you might expect a princess to say."
I imagine Margaret puffing a Woodbine behind the silver display.
He shows us Grand Admiral Doenitz's baton captured by the regiment when it arrested him.
We reach the medal cabinets. "These are from the Great War." He points at a cabinet in the centre of the room. "Did any of your family serve?"
"My husband's grandfather," replies Sarah. "He was gassed at the second battle of Ypres. We have his medals at home."
Our guide nods approvingly.
"Where do you keep the Whitewash Brigade Medal?" ask Sarah.
He looks surprised. "The 1894 Hong Kong Bubonic Plague medals. You know about them?" He leads us to another display.
There's a lithograph print of soldiers carrying corpses from a house. "Soldiers of the 1st King's Shropshire Light Infantry disinfecting plague houses," says the title. The silver medal is also there, a polished disc with a yellow and red ribbon. I can see the figure of death on it hovering over a Chinaman.
Sarah reads the card beside the medal. "An unofficial medal awarded to six hundred men known as The Whitewash Brigade who risked their lives collecting the dead for burial and fumigating houses."
There's a second plague medal, a gold one, in the display.
"They were given to the officers," explains our guide. "The sad thing is the men were permitted to keep the medals but forbidden from wearing them."
"Why?" asks Sarah.
"The medals were paid for by the people of Hong Kong. Because they were unofficial decorations, not awarded by the Crown, the men were not allowed to wear them. Shame really. What they did was incredibly brave." Our guide shrugs. "Some got turned into watch fobs. I believe others were made into brooches and given to sweethearts."
I produce the silver brooch from my pocket. "It was my great grandfather's. He was in the Shropshires. He gave it to his wife."
"Are you sure you want to do this?" asks Sarah. I know she means well.
I offer the brooch to our guide. "I'd like to donate it to the museum if that's possible."
He takes the brooch and studies it. "Yes. Yes indeed. I must say, that would be a splendid gesture."
We are on the train approaching Llandovery. It's dark outside. A noisy crowd of teenagers are on the platform. They fill the carriage. Cans and bottles are being opened and drunk. Ribald chatter echoes around the carriage. It's a party.
"Celebrating in Swansea tonight," says a girl in an alarmingly short skirt, "the end of A-levels." She giggles and takes a swig of cider.
We get off at Llangadog and watch the revellers' train vanish into the night.
"I wonder what time they'll come home," says Sarah and squeezes my hand.
I smile. "Long after our bed-time I expect," I say.
I'm tired but it's been a good day.