For 50 years the Great Western Railway used broad gauge which provided faster and more comfortable journeys than the standard gauge. Something had to be done about it.
At daybreak on Saturday 21 May 1892 conversion to standard gauge was started, and it was completed by 4am on Monday 23 May.
All of the rolling stock was replaced and 177 miles of track were replaced within 2 working days.
On 18 August 2018 work will begin on the signalling on about 10 miles of track between Seaford and Lewes and the line will be closed for 10 days.
It might be convenient at the same time to realign the tracks over Glynde Reach, about a mile south of Lewes.
The jolt at that point is uncomfortable to those who are expecting it and alarming for those who are not.
I don’t expect that this will happen.