There seems to be a lot of dealer promotions running at present, a sign of times for JLR? Updated- Waiting for a Scotland v England 6 Nations home win. 24th Feb 2018
Gone-1972 88 SWB Soft top
Gone-1981 24v FFR Lightweight
Gone-2009 Freelander 2 TD4 GS manual
Gone before it bankrupted me- 2008 Discovery 3 TDV6 Auto
2013 Freelander 2 SD4 GS Auto

What are the offers you have seen?
My local JLR Dealers definitely seem to have a lot of stock on their forecourt, and around their site generally, but I haven't spotted any real advertising.

If you have the ready cash, I suspect March may be a good month to exchange cars. FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 82k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)

I would say this is an excellent time to buy a new Land Rover if you don’t mind taking a major hit on depreciation as diesel cars become more & more unpopular

Or you could just buy the petrol option. 21MY Defender 90 S 3.0 D200

At a 10k premium

Every other manufacturer charged less for their petrol variants, except LR

Really?

P250 Velar is £2k cheaper than D240

The new Evoque petrol is around £2k cheaper than the equivalent hp diesel

D5 is couple of hundred £ cheaper (not much granted)

DS will no doubt be the same once the 2019 model is introduced 21MY Defender 90 S 3.0 D200

That has changed VERY recently then...

Mid-january, a petrol Evoque + petrol DS were 6k more than the diesel equivalent...

More expensive models had a higher price differential

I don't think diesels will become more and more unpopular - they have so many inherent advantages for some motorists that they will remain their first choice - particularly on the second hand market - unless of course the Government mucks it all up even further with more ill judged interventions.