Agree with what Fred says above other than all Platform staff will be trained, extra dates now being added in during the week to ensure this happens (which should have happened in the first place IMHO!), it is considered a very high priority to have all Platform staff trained. As for it being good news for passengers that the increase in 700 services is delayed: I guess so, but for the sake of a month I'm not sure it's worth getting excited about.
Anyway, those services that will now be starting on 26/03 are as follows:
Southbound
1P41 - 0510 PBO to KGX
2P91 - 0547 PBO to KGX
1P09 - 0726 PBO to KGX
1R47 - 0732 RYS to KGX
1P53 - 0847 PBO to KGX
2R41 - 1001 LET to KGX
2P45 - 1018 PBO to KGX
1T29 - 1158 ELY to KGX
1P63 - 1247 PBO to KGX
2P53 - 1419 PBO to KGX
1P67 - 1447 PBO to KGX
1P69 - 1547 PBO to KGX
2T61 - 1747 CMB to KGX
1P73 - 1803 HUN to KGX
1T25 - 2059 ELY to KGX
2V67 - 2334 WGC to KGX
Northbound
1P42 - 0722 KGX to PBO
2P06 - 0834 KGX to PBO
1T14 - 1014 KGX to ELY
1P50 - 1122 KGX to PBO
2P14 - 1234 KGX to PBO
1P54 - 1322 KGX to PBO
1P56 - 1422 KGX to PBO
2T22 - 1605 KGX to CMB
1P60 - 1622 KGX to HUN
2C28 - 1722 KGX to CBG
1T10 - 1914 KGX to ELY
2R38 - 1938 KGX to LET
2R50 - 2234 KGX to RYS
2P58 - 0034 KGX to PBO
Codes: KGX = Kings Cross, PBO = Peterborough, ELY = Ely
, CMB = Cambridge North, CBG = Cambridge, RYS = Royston, LET = Letchworth, HUN = Huntingdon