The diesel engine in my 2023 LDV T60 Max is dropping revs

Assuming there's nothing wrong with the engine causing it to lose power under load, this sounds like a case of the conditions causing the engine to struggle. Soft sand has a lot of friction and this literally grabs the tyres, causing the engine to load up and revs to fall. It's like a big, invisible hand grabbing the wheel and stopping it from turning freely. As you apply more power to counter this, the engine revs up, the wheels spin and the vehicle sinks even further into the sand and the cycle starts over again. Some cars with sensitive throttles are more prone this.

Experienced sand drivers know that the solution to this is to make the vehicle 'float' over the sand, rather than bulldoze through it. The best way to do that is to lower your tyre pressures. This allows the tread to 'bag out' and produce a larger footprint. And a bigger tread surface means more chance of staying on top of the sand rather than buried in it. It sounds simple but it really does work. Think of it as the difference between standing on thin ice in a pair of flat shoes versus stilettos.

How much pressure should you drop. We'd go from the usual on-road tyre pressures to about 18psi as a first step and then 15psi if the conditions are still causing problems. In extreme cases, you can go right down to 12 or even 10psi provided you're careful and keep your speed down. Don't forget to re-inflate the tyres once you're back on the bitumen.

Beyond that, if the problem is engine related, then a scan at your dealership should throw up a code to guide the mechanic on what's wrong. The vehicle is under warranty, so don't be backward in coming forward.