Try googling 'hens teeth' you may have more luck.These are extremely rare items especially if you want the Safety Devices one (RRL1976SSS). They have stopped making them for some years now. I have come across 2 over the past couple of years.
There appears to be very few suppliers who have ever made ladders for Freelanders in general. You could have a word with Brownchurch to see if they supply.
Adrian