My list says Ovaltine is okay so I got it into my head that Horlicks is too.
As I wanted to get an early night last night and I was staying away from home, I had a cup of hot Horlicks. Not very successful at all. I woke at 3.30am am and spent much of the rest of the night running to and from the bathroom. It seemed to have an effect on the bladder.
Looking at the ingredients there is no obvious reason. It is barley malt which should be okay. However it does contain an unspecified vegetable oil.
I had a letter from the dietician saying she is still researching outstanding issues. These include rapeseed oil and redbush tea. From following some of the links that have been posted on this site, I discover there may well have been only one systematic scientific study of salicylate levels. As they can apparently vary quite a lot, depending on the soil - so the dietician said, this would seem inadequate.
I am guessing that rapeseed oil is okay but never asked about sunflower oil which is not on the list either.