My dealer told me that JLR had embargoed road use of all DSs the other week, with no explanation from them. This was rescinded mid last week and is why I suddenly got a call to say I could have one for the day, and chose last Thursday. I think it was just a precautionary 'hold' while they checked something out.
When I took it back, my dealer said that my 27 March date had now become 20 - 27 March.