My final thoughts on the cutting: on the 1891 OS (available online at
http://www.old-maps.co.uk) there is a spot height of 14ft opposite Southwold station and one of 42ft near the top of the High Street. On the modern 1:25k OS the 10m contour is just to the east of the cutting, so the edge would be <33ft ; allowing for the fall to the bridge, this would confirm the c.20ft depth.
It is interesting to note that the 0m contour is crossed as the line emerged onto the marshes, the embankment itself forming the boundary between Busscreek and Woodsend Marshes which lie below sea level. The embankment - such as it was - didn't stop the North Sea trying to interfere with trains, as can be seen in plate 71 of
Branchline to Southwold. The line descended from the bridge at 1:66 towards Southwold and from my memories of blackberry picking, it was pretty much at the same level of the marshes - was the SR the only British narrow gauge line to be below sea level?
The location of the footbridge is not shown on the 1891 OS as it was built in 1904, but the pic of the cutting suggests it was roughly at the midpoint of the curve which would be the deepest section. The 1:25k OS does show a footpath aiming for this point which then diverts to the west end of the cutting, probably due to the removal of the 'bridge.
I think it's high time the SR got a quality, detailed history. This is not to denigrate Messrs Taylor & Tonks, but it would be lovely to see something of the same ilk as the Wild Swan books on the Ashover, Talyllyn and Vale of Rheidol. As a starter, there are various items available at the Public Record Office, including plans and I think the company minute book. As a further indication of the growing power of the interweb, I have just found that there is a 1928 photograph of a train in the cutting in Suffolk Record Office, Lowestoft!
Enough ..
Patrick