Restoration was started in 2005, with the original intention that a return to main line service would take place in 2008. As of the start of 2018, restoration is still ongoing. It was announced in an issue of "Steam Railway" magazine that plans to run "Pendennis Castle" on an excursion trip with preserved sister 7029 "Clun Castle" to commemorate the end of steam and the end of the Castle Class on the Western Region in March 1967 would not go ahead as 4079 would not be restored in time for the anniversary in 2017. It was later announced that following Didcot's decision to withdraw from running on the mainline, on completion 4079 will only be run at Didcot and on heritage railways.