Welcome to the winter update of Forgotten Relics.

Catesby Tunnel is straight out of the top drawer: a glorious example of the lengths to which Victorians would go to engineer their railways through adverse landscapes. The adversity on this occasion was social, not topographical: the local estate owner was unwilling to have the vista from his stately pile blighted by filthy mineral trains.

The tunnel was erased from the railway's inventory in 1966 when a shortsighted act of vandalism shut the Great Central's London Extension. If open today it would resolve many of the capacity issues afflicting the West Coast Main Line. But we are where we are. Instead facing us is the rather perverse prospect of the automotive industry benefiting from Catesby Tunnel with the emergence of plans to convert it into an aerodynamic test facility. It was of course the advent of cheap motoring that brought the curtain down on much of our railway network, including this bit through Northamptonshire. Anyhow, we've spoken to the man behind the idea to hear what it's all about.

And if that's not enough, prospects are looking brighter for other disused tunnels as campaign groups form to promote a rebirth for two of considerable significance: Rhondda and Dundee Law, with an eye on cycle path and tourism use. Each proposal brings it's own challenges and things are very much in their infancy, but you can get more insight - or lend your support - through the associated Facebook pages. Rhondda's is here (you need a Facebook account); Dundee Law's is here.

We celebrate two other tunnels north of the border in this our first 'seasonal' update. Despite its relatively modest size, Lasswade Tunnel has a lot going on inside with strange 'ledges' forming at springing level and the biggest kink you've ever seen, presumably the function of a setting out error during construction. It's one of those with much to offer as it plots an S-shaped course under Broomieknowe.

There's no real drama in Balgray Tunnel - visited by K-Burn and chums - which accommodated a branch of the Lanarkshire & Dumbartonshire Railway. Probably its most notable feature is outside at the southern end where Kelvinside's fabulous Renaissance-style station building forms the top of the entrance. Having evaded the nearby infill, the platform ends penetrate the tunnel's security fencing, behind which is a surviving block of urinals. Very convenient.

Wheatley Viaduct is one of those structures that's acutely Northern; it couldn't be anywhere else. A row of characterful terrace houses stands in the shadow of one span. Built for the Halifax High Level Railway, its stonework looks great when the sun gets to work on it, but one arch is looking decidedly dicey as bricks are jettisoned from behind the voussoirs.

Not suffering from any such problems are the austere plate girders of Coronation Bridge, crossing a flood alleviation channel to the east of Spalding. And there's no reason why there should be - it only opened in 1953. Despite being a structure with no pretentions, it's sad to see the hard work needed to assemble it go to waste. It adds some interest to what otherwise is a rather bland scene.

Just a quick reminder that our 2015 Forgotten Relics calendar is still available to buy. Just in case you're wondering - no, this hasn't been adapted to our new seasonal format: there's still a picture for every month! Order yours by clicking here or follow the 2015 calendar link in the sidebar.

I would like to doff my cap once again to my website coding chum JD who has upgraded our page listing Ireland's Disused Tunnels to have the same functionality as the main UK database. This means that you can now sort the list in length/opening/closing/company order, rather than just alphabetically, as well as seeing aerial imagery of the portal locations.

And finally, our video project for 2015 is likely to be a celebration of the North's great disused viaducts, viewing them from the air. We've produced a trailer which you can see above. Which viaducts do you think we should feature?