Labour was very early on hijacked by British aristocrats and bourgeoisie, unlike other European "socialist" parties which at least had a radical Marxist past (eg the SPD). The whole point of it was to represent part of the establishment who argued "you know, maybe we shouldn't push the poors too much. We can even gain compliance from them by sharing the spoils and calling it Socialism". So its turn to Blairism and increasing similarity to US Democrats is not at all unexpected in hindsight.