no, it is a snack period at around 11am to tide one over until lunch. In the context of this sign, I think the meal in the middle should be a called light lunch rather than elevenses, given that there is otherwise no actual lunch period.
British eating habits are similar to those of Hobbits. Breakfast, Second Breakfast, Elevenses, Lunch, Afternoon Tea, and Supper. I tend to have more but I'm more like a super-Hobbit.
Dinner could refer to lunch in this case, as it would usually do in the north of England; whereas what mostly southerners call dinner is what would be called tea in the north.
Similarly, here in the States in the rural south they have dinner at noon (which is the big meal as you would think of dinner) and then supper for the evening meal, which often consists of leftovers from the earlier dinner. I experienced this years ago staying with my parents at a relatives house in a small town in South Carolina.
