Surprised that you still have colonies on site; most reserves do not permit honey bees due to the risk of forage competition for the other 260 species of bee and all other pollinators.
It is not certain that competition for forage deprives smaller pollinators, but as research cannot cope with the variables of available seasonal forage & insect populations, the authorities operate a precautionary principle and exclude.
London Wildlife Trust allowed honey bees until about 5 years ago, but at a West London nature reserve a public stinging calamity gave LWT head office the opportunity to fall in line with Natural England policy (and to reduce liability).
Pity, because the honey company I worked for had hives on site, and I'd just persuaded the manager at
Woodberry Wetlands of the value of honey bees as a shop window to draw the public into wider environmental debate, and he'd incuded it in his educational programme.