2005 Part A Q2 - Answer

[alexgoei]

Dear Alex,

As the 'nasty, nasty points' writer, I can confirm that you shouldn't get too bogged down in the small stuff. As long as you can handle the main elements of the CTs, and it seems that you can, you have plenty of time to get the rest.
Try to understand exactly what the 'extra' locking does, and once you can relate it to a train move (or more likely what you are preventing) then it will become clearer.
Good luck.
Lynsey