Finally found the place due to there being no signage. Was let in the door by a staff member going out for a cigarette. Sat by what appeared to be a reception but there was no receptionist. Finally asked by a guy going to the toilet if I needed anything and too his credit he went to find someone. A lady came back and was rather surprised that I was there as there was no one from HR present to do the interview. Was then taken off to a small office to be interviewed by two ladies who clearly were unprepared and did more talking than listening. If offered a job here I'll not be accepting the position as I've other interviews I'm waiting to hear back on and this place didn't give the impression that they'll be around long.
Also, I checked my interview invite email and yes, I did turn up at the given time and correct day.