Not without significant disassembly of the engine. There is no simple external visual cue to determine if the guides have been replaced. You can try calling the local LR dealer and provide the VIN of the vehicle. They may be willing to check service records. This would only let you know if an actual JLR dealership did the work. If a PO had the guides/tensioners replaced by independent mechanic, you wouldn't know. You could also ask the seller if they have any of the vehicles service records.
Dealers are not always the ones that handle the TSB for the the guides and tensioner upgrades. Dealers usually only handle TSBs under the original warranty period then it is up the what ever third party extended warranty if any.
Long and short you need a printed receipt showing the guide and tensioner upgrade has been done. If that can not be provided by the seller then you sadly must assume it has it had not been done. It is a positive selling point so there would be no reason not to share it being done.
Thank You Everyone for your inputs - I do appreciate it. I will ask for the service history and see what they tell me. I've owned and serviced all types of vehicles over the years, foreign and domestic, some had timing belts and some had timing chains. I used to think that timing chains were superior to timing belts, but when you take into account chain guide and tensioner issues, a timing belt system may actually be better in some cases.