Yes, Colin, I do have a trickle charger I used to use for my motorcycle batteries on the basis that they were ridden infrequently. I wouldn’t expect to have to use it on a £50k+ car that is driven over 10k miles a year… In any case, my car is too far from the house to plug the charger in.
As advised by the AA and others on these forums, I have been putting the car into ‘Ready Mode’ when hoovering the floor mats or loading / unloading the boot - something I have never had to do with any other car!
I have raised the matter with Lexus again.