Is it the 313s that are being leased for a peppercorn rate? IIRC there is one class that had a superbly cheap leasing cost, if not the 313 I wonder if it was those 455s that just went...455s only went because the license / lease hire, ran out. The cost to renew the license / lease hire went up by quite alot, so Southern decided to not renew it.
The 313's license / lease actually runs out at the end off 2023.