I'm sorry, but using the term "fine" to describe the food suggests to me that even you concede the food is little more than acceptable. There are precedents for superior food at equivalent prices in countless park and high street cafes within a 2 mile radius of the Horniman - one within a five minute walk.
When i say "fine" i mean really fine ,i certainly DO NOT concede the food is little more than acceptable, the bottom line is if you are really not happy with the place, simple! don't go there!!!