Yes this is true as I can confirm from my visit to Platts at S-o-T this morning!
After some detective work by one of the technicians it was found that a section of trim adjacent to the running lights was removable giving access to the tap hole. The section was moulded to be be in keeping with its surroundings and had no visible fixings - It could not be seen from under the front end because of a cowling and required quite a clever pull and slide movement to release it.
I suggest Frankia owners of this vintage might like to check it out on their outfits - it's not obvious!
V