when will tomatoes go red?!

I've got 3 moneymaker tomato plants & they have all had green tomatoes on for quite some time now.....but after many weeks they are still green & no show of turning red. Being new to all this this year I just wondered when are they likely to turn red?

I am in Vienna, somewhat south of the UK, and my tomatoes are also not red. I thought it was because I planted them too close together (I am a novice at gardening), but we also haven't much sun the last couple of weeks.

Will they ever turn red I wonder??