Ignoring rumoured cascades such as loco hauled for TPE or LM taking on EMUs which Northern and TPE are releasing I'm aware of the following cascades have been reported in rail magazines, franchise agreements, presentations etc.
2016
5 x 170s from Scotrail to Southern***
4 x 170s from TPE to Chiltern
12 x 319s from GTR to Northern*
10 x 387s from GTR to GWR
* RAIL has reported a 2016 date despite new routes not being electrified until 2017, possibly to allow them to be refurbished?
2017
3 x 150s from LM to Northern
15 x 150s from GWR to Northern
19 x 387s from GTR to GWR
21 x 365s from GTR to GWR
6 x 153s from ??? to LM**
** I don't think it's been confirmed they will come from GWR even if it looks likely.
2018
2 x 150s from GWR to Northern
5 x 156s from Scotrail to Northern
8 x 158s from Scotrail to Northern
16 x 170s from Scotrail to Northern***
*** These two combined make up all the 170s Scotrail are releasing now the lease has been extended on another 13 of the 170s which Scotrail have.
Are there any other confirmed cascades?
2016
5 x 170s from Scotrail to Southern***
4 x 170s from TPE to Chiltern
12 x 319s from GTR to Northern*
10 x 387s from GTR to GWR
* RAIL has reported a 2016 date despite new routes not being electrified until 2017, possibly to allow them to be refurbished?
2017
3 x 150s from LM to Northern
15 x 150s from GWR to Northern
19 x 387s from GTR to GWR
21 x 365s from GTR to GWR
6 x 153s from ??? to LM**
** I don't think it's been confirmed they will come from GWR even if it looks likely.
2018
2 x 150s from GWR to Northern
5 x 156s from Scotrail to Northern
8 x 158s from Scotrail to Northern
16 x 170s from Scotrail to Northern***
*** These two combined make up all the 170s Scotrail are releasing now the lease has been extended on another 13 of the 170s which Scotrail have.
Are there any other confirmed cascades?