This is one of the considerations I have to make - the current one only just fits through the doors as I found out when it took me quite a while to figure out how to move it out when I was having the carpets done last month. If it gets replaced, it will just be cut up and moved out in pieces.
Pictures are OK, but they don't give an actual measurement and it seems that a three seater can be anything from 150cm (too small) to 210cm between the arms. Looking around last night, Next seem to be very good with showing the internal sizing and options AND the local store has a furniture department...
It's only for occasional use as I still prefer the recliner armchair for a quick doze and this is also on the potential replacement list.