Even at this relatively early stage of the relationship our interests are diverging, due largely to his preoccupation with trains. He has, at the last count, five train-sets, and has only recently emerged from a determined phase of refusing to wear anything except a blue, hand-knitted Thomas the Tank Engine jumper.
In contrast to rusty rails and smoky engine sheds, I yearn for freedom and fresh air. On holiday, I wake bright and early and set off into the hills. It was with dismay, then, that I discovered that the cottage we had booked for our summer holiday in western Cumbria was only a few hundred yards from a station on the narrow-gauge Ravenglass and Eskdale Railway.
Parenthood, I am told, is all about flexibility, and despite travelling on as many small-scale railways in the last two years as Sir Topham Hatt has eaten hot dinners, my partner and I tried to make the best of things. Our nearest station was Irton Road, midway along the line from Ravenglass, the only coastal village in Lake District National Park. The beautiful woodland of the Eskdale valley is at its best on this stretch of the line, while it's all change at Dalegarth Station at Boot, a village in the shadow of Scafell Pike, England's highest mountain. This charming 12-mile, nine-station railway is known by locals as "la'al ratty", Cumbrian dialect for "little narrow way", and it toot-toots all year long through a relatively unvisited corner of the Lakes.
Arriving at the station in an unsustainable state of excitement, Louis scampered off, toying with the points and inspecting the track at eye level. I passed the time giving chase and fretting about derailment and decapitation. Eventually the train arrived and puffed to a halt, and a ruddy young man with a conductor's hat ambled along the platform to collect our fare.
The gleaming green steam engine was called Northern Rock; once on board, clutching his very own snipped ticket, my beaming son was the happiest boy in Lakeland. La'al ratty was originally built to transport iron ore from above Boot village to the mainline railway at Ravenglass. From here, trains chuffed along rails three feet apart to the steelworks at Workington and the shipyards at Barrow. The first traffic travelled in 1875, passengers joined the following year.
Following closure and bank-ruptcy, in 1915 it made the transition from a narrow-gauge railway to a miniature railway - these things matter to rail enthusiasts - with the tracks relaid 15 inches apart. The line closed again in 1953 but reopened in 1960 thanks to the enthusiasm of the Ravenglass and Eskdale Railway Preservation Society and the money of two businessmen. It has been puffing away ever since.
Despite the presence of steam, metal and startlingly loud whistles among some of England's loveliest scenery, la'al ratty has charmed allcomers, even that purist of the Lake District, Alfred Wainwright. The author of idiosyncratic hill-walking guides travelled by public transport, so the reopening of the line would have made his job easier.
In Wainwright's Walks from Ratty, a compilation of 10 walks accessible from stations on the line, the author describes the route thus: "Eskdale, one of the loveliest of Lakeland's valleys, descends from the highest and wildest mountains in the district to the sands of Ravenglass in a swift transition from grandeur to beauty, from bleak and craggy ridges to verdant woodlands and pastures watered by a charming river... It remains today little changed since the first settlers discovered and cultivated with loving care this perfect Arcadia in the hills."
A railway through scenery this beautiful raises the question of whether it is better to travel than to arrive. In respect of la'al ratty, from my point of view the attraction is in arriving -whereas my son's interest- it should go without saying by now - lies in the travelling. From an arrivee's perspective, there are two pubs in Boot, the equally decent Burnmoor Inn and Brookhouse Inn. There's a small art gallery and a working corn mill. Heck, there's even a Post Office.
Once in Boot, families in search of a good walk have a choice: strap the little one(s) into a carrier or papoose and set off into the hills; or go separate parental ways. We chose the latter and, on condition that I returned in time to catch the last train home, I took Wainwright and a packed lunch for a six-mile walk in the hills. Meanwhile, my partner took Louis for lunch and a scramble in the pub garden, followed by a wander in the woods and some stone-throwing by the stream.
The Sca Fell peaks are the nearest mountains, but despite their looming presence they are still a good distance away. In his book, Wainwright recommends the walk from Boot to Burnmoor Tarn instead. As I climbed, intermittent toots sounded in the valley below with the melancholy echo of a ghost train; and this is indeed a ghostly area. Over the centuries, the path to Burnmoor has been used as a pony route and a droveway for sheep, but it is better known as the "coffin route". For years, the dead were carried on this path from the remote and distant area around Wasdale Head for interment at St Catherine's Church in Boot.
The path starts steeply and crosses Whillan Beck. It is an easily navigable and well-trodden route - think of all those dead bodies - and after passing through a series of gates, I emerged on to open moorland, passing cairns that may suggest the route was also known to ancient Britons.
After the better part of two hours I was alone on Burnmoor Tarn, with the summit of Scafell Pike a tempting 90 minutes away. As I lunched on a cheese-and-pickle sandwich and a cup of flask coffee, the silence was deep and unwinding. There was no traffic noise, no mobile telephones and, for a couple of hours at least, no little boys saying, "Chuff, daddy, chuff, daddy, chuff-chuff-chuff."
All aboard on the little lines
The Ravenglass and Eskdale Railway (www.ravenglass-railway.co.uk) runs year-round. Adults from £8.60, children half-price.The 72-mile Settle-to-Carlisle line (www.settle-carlisle.co.uk) offers walks in the Yorkshire dales and Cumbrian fells. Adult day-return £17.50, children half-price. The Romney, Hythe and Dymchurch Railway (01797 362 353, www.rhdr.org.uk) in Kent operates year-round except November; fares from £6.10. The Ffestiniog Railway (www.festrail.co.uk) runs from October to March through Snowdonia National Park. Adult fares from £12.50, children £7.70.