On the trail of the abandoned South Eastern Railway tunnel at Riddlesdown

Walking over Riddlesdown recently, I took the opportunity afforded by recent conservation work, scrub-clearing and path-creation to have a closer look at the southern end of the Riddlesdown railway tunnel and the railway cutting running southwards from it. As a result, I came across a somewhat enigmatic elongated mound alongside and on the east side of the cutting, between the tunnel portal and the skew bridge carrying the Riddlesdown Road bridleway over the line.

Caleb Evans has this to say about this cutting as observed between 1867 and 1870:
"It is frequently the practice in constructing railway tunnels to form a temporary cutting and a temporary mouth, and afterwards to cut the ground further back beyond such temporary mouth to the spot where the permanent mouth will be situated.
The southern end of the Riddlesdown tunnel is at present [1870] in this condition: there is an upper cutting in the slope of the hill about 50 feet deep and about 400 feet in length, within and below which, at a distance from the north end of 188 feet, is the temporary mouth of the tunnel, and a lower cutting about 30 feet deep extends 350 feet from this point.
The lower cutting by the temporary mouth of the tunnel is still in a rough state …"

Although Evans gives a longitudinal section to make this clear, the Ordnance Survey's 6" to 1 mile sheet, surveyed in 1867, does not clearly depict this 'double cutting.' Nor does it show the elongated spoil-bank running parallel with the cutting on its east side. This bank, tree-covered and difficult to see as a whole, is substantial and clearly lying upon the natural land surface. It is aligned approximately parallel with the railway, and is quite unlike a chalk-pit spoil tip; and, anyway, there is no chalk pit here. Neither does the bank feature on the second (mid-1890s) or subsequent editions of the Ordnance Survey's six-inch map.

So whence this substantial bank which (whatever its date) appears to have been missed by the Ordnance Survey?

The possibilities seem to be:

1. It is spoil from the (lost) working shafts of the abandoned South Eastern Railway's Riddlesdown tunnel, which is known to have been commenced on 11th March 1837 but abandoned, and the equipment removed to Tonbridge, in September 1938; against this, it has to be admitted that the intended SER tunnel was reportedly to have been 528 yards long (shorter than that actually completed (836 yards) and still in use) and to the west of it;
2. It is Warings' spoil from their work of 1865-1867 from the abandoned Surrey and Sussex Junction Railway;
3. It is Joseph Firbank's spoil from his work, 1880-1883, completing the line for the Croydon, Oxted and East Grinstead Railway;
4. It is something else entirely!

Possibilities (2) and (3) seem inherently unlikely, as the whole modus operandi of railway contractors was to transfer all spoil from cuttings downhill under gravity to be used in embankments further down the line. Carrying so much spoil uphill, and dumping it on the uphill side of the cutting, would have been an expensive and pointless operation – especially as it would all have been eminently suitable for embankment construction.

Possibility (1) makes most sense, but implies an error in recording the original SER intentions and work done. Tunnel spoil was generally lifted up the working shafts and dumped on the land above the tunnel. The main Brighton line Merstham tunnel (made 1838-1841) was made like this, as can be seen on the Ordnance Survey's first edition six-inch map. If the enigmatic bank is abandoned South Eastern Railway tunnel spoil, this would imply an unfinished tunnel (and more or less blocked shafts) east of the current Oxted line and extending further south than the second (completed) Riddlesdown tunnel.

John Matthews has informed me that there was once a rifle range in this general area, but the massive and rather irregular feature seems unlikely to have been thrown up to protect passing trains from stray bullets. Can any member suggest anything else in favour of possibility (4)?

On a further visit to Riddlesdown, I had a look at the land below which the unfinished South Eastern Railway tunnel should be if it was indeed to the west of the existing Riddlesdown tunnel. This would be to the rear of the houses on the west side of Ingleboro Drive. I found three interesting hollows or depressions in Coombes Wood, in what appears to be land covered with Clay-with-Flints. One or more of these could conceivably be backfilled shafts in which the filling has settled. But as this western alignment would have meant a shorter tunnel than that actually built (which is 836 yards with two permanent spoil-extraction shafts), one might expect two shafts or perhaps just a single one, but hardly three. I have yet to plot the exact positions of these depressions, to see if they have a common alignment. I noticed no spoil banks representing the contents of the unfinished tunnel. But such banks are not readily obvious at the existing tunnel shaft locations either – the brick towers marking the shaft tops are at the upper end of Dalegarth Gardens, and in shrubbery at the corner of Eskdale Gardens and Honister Heights. A more thorough exploration of Coombes Wood is clearly needed.

Paul W Sowan

Bibliography

Evan, Caleb (1870), On some sections of chalk between Croydon and Oxtead. Geologists' Association.

Gray, Adrian (1990), South Eastern Railway. Middleton Press.

Herepath's Railway Magazine, April 1837.

Sowan, Paul W (1999), Messrs. Warings' and Joseph Firbank's contributions to building the Oxted line, east Surrey, 1865-1867 and 1880-1883. Local History Records of the Bourne Society 39, 51-65.

Turner, John Howard (1977), The London Brighton and South Coast Railway: I. Origins and formation. B.T. Batsford Ltd.

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