Annual Company Party

I need someone to organise our annual company party (to be held at the end of September). We want to leave the office at 4 on the day (we are based closed to Hammersmith) for some pre-dinner entertainment (you will have to come up with some suggestions, last year we took a duck tour), followed by dinner for around 50 of us at a central London location (zone 1 or if zone 2 it needs to be west), followed by entrance to some place for dance and drinks.
We are looking for someone that has done this kind of thing before and will take care of all the organising (putting together the ideas, booking venues/transfers, writing emails with instructions for everyone etc).
You will not need to be present on the day but reachable on the phone in case something does not go according to plan.