Relaxing amid the sumptuous splendours of a 1920s Pullman car at Bath Spa station last week, I was surprised to encounter a potent reminder of home. This was the InterCity 125 locomotive that I have good reason to claim as 'mine'. I was among a small group of guests present at Oxford station when it was given the name Oxfordshire 2007, in honour of the county's millennium. I had seen power unit No 43198 only once since and was delighted to see it again, not passing this time but stationary, framed in the window of my compartment.

After the naming ceremony in February of last year, we had travelled in a bizarrely constituted train (two power units, one coach) for lunch at Didcot Rail Centre. Sitting opposite me on the short journey was the novelist Colin Dexter. Talk turned to crime fiction and I was delighted to find he shared my low(ish) opinion of the work of Dorothy L.Sayers. Last Saturday I noted that Miss Sayers and Colin both had their place in The Times's list of the Fifty Greatest Crime Writers. Not present, however, was a fine writer who also figured in our chat last year. The omission of Freeman Wills Crofts could be regarded, I suppose, as reasonable - a matter of opinion concerning a largely forgotten writer - whereas the exclusion of G.K.Chesterton, with his legendary Father Brown tales, was surely an absurdity.

Wills Crofts was a contributor to what is called the Golden Age of crime fiction, a period which happened to coincide with a Golden Age in travel. He celebrated this in his novels, many of which have a railway setting. He was just getting into his stride in 1925, the year in which the Birmingham Railway and Carriage Company built Pullman coach Ibis. This was the lovely carriage, tricked out with gleaming brass fittings and marquetry panels depicting Greek dancing girls, in which we took our sentimental journey to Bristol last week. It is the oldest of the 11 used for excursions by the Venice Simplon Orient Express.

During its many years of service, it was used both on the Golden Arrow boat train between Victoria and Dover and the Cunard trains to Southampton. On both, it would have been hauled many times by Clan Line, the gleaming green giant at the head of our train to Bristol.

Built in 1948 and retired by British Railways almost 20 years later, the locomotive is one of designer O.V.Bulleid's "Merchant Navy" Pacifics. These were intended for the heaviest and fastest expresses, though the Southern Railway managed to get permission to start building them during the Second World War on the grounds that they would be valuable as a means of shifting freight.

I have a particular admiration for Clan Line, as it was depicted in its original streamlined (technically called 'air-smoothed') form in one of the picture books that inspired my abiding love of railways as a child. It was also a notable machine for speed. In his book Speed Records on British Railways, the railway historian O.S.Nock identifies it as the fastest member of the class, credited authoritatively with achieving a speed of 104mph on the Atlantic Coast Express at Axminster.

He writes: "In the last weeks of steam traction on the Bournemouth line certain of the more sporting drivers were making very hard runs east of Basingstoke in satisfying their own ego and delighting amateur enthusiasts. Several instances were claimed of speeds of more than 100mph, but nothing to surpass the performance of Clan Line seems to have been fully authenticated."

After that, it seemed slightly demeaning for her to be consigned to the slow lane (albeit at a thrilling 70mph) of Isambard Kingdom Brunel's line back from Bristol to London. As she pounded along, to the delight of so many observers at the lineside, a succession of InterCity 125s of the class of Oxfordshire 2007 raced past, going nearly 60mph faster.

Clan Line will be visiting Oxford tomorrow with a VSOE Pullman excursion from London. The engine will arrive at noon, at the rear of a train headed by a diesel locomotive, and depart under her own steam from Oxford station just after 6pm.