Many of the Mark 3s are scheduled to be withdrawn by 2020.
Great Western Railway and London North Eastern Railway sets were replaced by Class 800, 801 and 802 sets.

The East Midlands Railway sets are also scheduled to be withdrawn by the end of 2020.
Former Great Western Railway Mark 3s have been leased to Abellio ScotRail since 2018 for use on Edinburgh/Glasgow to Aberdeen/Inverness and Aberdeen to Inverness, routes.
Great Western began trials of shortened HST sets with new power-operated external doors in 2018, and intend to run 11 of these 'Castle' sets on local services on the main lines.

The Caledonian Sleeper Mark 3 sleeper sets were withdrawn in October 2019.
Grand Central then withdrew their Mark 3s in 2017.
These were transferred to East Midlands Trains.

Great Western Railway and London North Eastern Railway withdrew its Mark 3 sets in 2019, with GWR reforming many Mark 3 sets as 4 car refurbished "Castle" sets.

Greater Anglia withdrew its Mark 3 sets in March 2020.
Many of the Mark 3s are scheduled to be withdrawn by 2020. Great Western Railway and London North Eastern Railway sets were replaced by Class 800, 801 and 802 sets.
The East Midlands Railway sets are also scheduled to be withdrawn by the end of 2020. Former Great Western Railway Mark 3s have been leased to Abellio ScotRail since 2018 for use on Edinburgh/Glasgow to Aberdeen/Inverness and Aberdeen to Inverness, routes. Great Western began trials of shortened HST sets with new power-operated external doors in 2018, and intend to run 11 of these 'Castle' sets on local services on the main lines.
The Caledonian Sleeper Mark 3 sleeper sets were withdrawn in October 2019. Grand Central then withdrew their Mark 3s in 2017. These were transferred to East Midlands Trains.
Great Western Railway and London North Eastern Railway withdrew its Mark 3 sets in 2019, with GWR reforming many Mark 3 sets as 4 car refurbished "Castle" sets. 
Greater Anglia withdrew its Mark 3 sets in March 2020.
British Rail Mark 3