The present letter reports unusual high fluorescence anisotropy of excited state intramolecular proton transfer (ESIPT) prone 2-(2'-hydroxyphenyl) benzoxazole (HBO) in water followed by its imidazole (HBI) and thiazole (HBT) analogues. The low fluorescence anisotropy of the acetate compound of HBO in water reveals the key role of the hydrogen bonded cage-like probe-water cluster for the findings in water. Formation of the aquated cluster is controlled possibly by the combined effect of the electronegativity and mesomeric effect of the heteroatom away from the ESIPT site. The work invites further explorations, preferably from computational perspective, for a proper explanation.