I hadn’t realised the govt had asked for bank stability guarantees. I can understand why and think it is a good idea. On my area of the SE we currently have the Redhill-Tonbridge Line Crowhurst JN slip site that will be out for months, minor slips near East Grinstead and Haywards Heath as well as piling work at Wivelsfield to alleviate a slip in progress before it closed the main line.
We also have had historic slips on the Quarry lines near Redhill and Hooley, the main line at Earlswood and also on the Eastbourne line near Ripe. Most of these caused by excessive rainfall and poor quality “made up” ground failing embankments or excessive rainfall on very old cuttings.
So getting it right in the first place may save many pounds and train delays later.
For my two pence worth I’d rather have seen the money spent improving the Northern, East-West links between major cities before extending down towards London.