Now, in June 2020, the Class 483 is well and truly on borrowed time. Had the current world crisis not come into being it is likely that the deliveries of the first Class 484 units would be imminent if they had not already happened. As it is they are, it would seem, postponed until September at the earliest.
This was mentioned at the bottom of an Island Echo article which brought our attention to the fact that the Island Line service is back to one train again as of today due to the failure of either 483006 or 483008, we are not yet sure which. One of the units also failed for a month from mid-September last year, a sign of the deteriorating reliability of the stock as the youngest unit rapidly approaches its 80th anniversary. It is now patently clear to all that the stock will have to be replaced at the soonest possible opportunity, which is why the LTTG is now making moves towards being ready to make negotiations for acquiring one of the units.
The article may be found here - https://www.islandecho.co.uk/island-line-running-one-train-due-to-fault/