In Search of Overwintering Herald Moths in the Kelmarsh and Oxendon Tunnels
I had planned to have a walk around one of our Northamptonshire woodlands at the start of this week, but the drizzle in the morning, followed by the prospect of the heavy rain that was forecast to hit the county by midday, forced me to make a last-minute change of plan. So instead, I headed up to the north of the county to walk along the Brampton Valley Way and to shelter from the rain by exploring the Kelmarsh and Oxendon Tunnels to look for overwintering Herald moths. For those who haven’t visited this area, it is well worth the trip as the tunnels are fantastic examples of Victorian engineering. The tunnels sit along the now-disused Northampton to Market Harborough railway line which opened in 1859. Due to their narrow bore, they were nicknamed the “rat holes” by the train drivers of the day. The line ceased to be used as a railway in 1981 but the land was purchased with the intention of creating a linear park, and in 1993 the Brampton Valley Way was opened forming a footpath and cycle route between the two towns.
The first tunnel I decided to visit was the northern one which is known as the Oxendon Tunnel. After parking along the short road just off the A508 I made my way north along the Brampton Valley way and before long the imposing entrance to the Oxendon Tunnel came into view. Each tunnel has a neighbouring tunnel running parallel to them which can be seen by climbing the adjacent bank, but due to safety reasons they are locked and cannot be entered by the public.
The imposing entrance to the Oxendon Tunnel
In the past, this tunnel has been the best one to look for overwintering Herald moths and I have also found Peacocks here over the years too. On this occasion, there weren’t many moths to be found although the best area to look, in the roof of a refuge on the right-hand side as you enter the tunnel from the south, came up trumps again and 6 could be seen along with an overwintering Bee (edit: this is actually one of the Bee mimicking Hoverflies, thanks to T Pendleton for correcting my miss-identification). Most of these refuges, which were built to add an escape area for anyone working in the tunnel should a train enter, are bricked up but in this southerly refuge half of the breeze blocks have fallen in providing a great overwintering spot for overwintering Heralds.
Two of six overwintering Herald moths, and an overwintering Bee mimicking Hoverfly, in the southern most refuge in the Oxendon Tunnel
I couldn’t find any more moths in this tunnel, so I made my way out and retraced my steps south along the disused railway line and back to the car. From here I drove south along the A508 before turning left towards Arthingworth and parking up in the Brampton Vallet Way car park there. You may notice the large fenced-off area to the north of the car park, this is the site of the now-disused Kelmarsh Defence Fuel Storage Depot which used to supply the local airfields with aviation fuel. Although on this occasion I drove between the two sites it is quite a nice walk if you park up at one of the sites and walk the Brampton Valley Way between the two. I only took this lazy option due to the weather as I would have been soaked by the time I’d walked from one tunnel to the other and back again. The Kelmarsh Tunnel is just a short walk south from this car park and it wasn’t long before I found myself at the northerly entrance to this equally impressive Victorian structure.
The northern entrance to the Kelmarsh tunnel
Each tunnel is around 450 yards long and they both have a ventilation shaft around halfway along their length. These shafts are just as magnificent as the tunnel entrances and it is well worth looking up to admire the Victorian brickwork. For anyone who is interested in photography, it is quite hard not to invoke the inner “poser” in oneself as the below selfie photo shows!
An obligatory “selfie” in the Kelmarsh Tunnel
Back to moths, I had a good look around the tunnel but I could only find four Herald moths, all of them on the walls near the northern end. Most of them were quite high up but one was low enough to get a photo of with the macro lens on the camera.
A Herald moth in the Kelmarsh Tunnel
Although not many moths were found it was still great to be able to find a few and it is always a worth while trip to come and explore the tunnels. If you are planning on visiting please note that there is no lighting in the tunnels so make sure you bring a torch! Parking a short walk away from the Kelmarsh tunnel can be found at SP7460680469 and parking just south of the Oxendon Tunnel can be found at the end of a lane at SP7382182368 but please park considerately and don’t block any gates.
The last photo of the day was of a very autumnal looking Brampton Valley Way framed by the imposing northern portal of the Kelmarsh tunnel.
