All 3 chickens stopped laying today

[Farmyard Farmer]

Our 3 Rhode Island Reds stopped laying 2 days ago, all at the same time.
They have been giving us in average 3 eggs a day since they were pullets 6 months ago.
We extended their cage from 2x2 to 2x4 yesterday and introduced a new chicken to the flock 2 weeks ago (which is still separated from the others).  Could this be the reason?

[Beantree]

Any change to their environment can have this effect @Farmyard Farmer, because they will only lay when they feel secure enough to raise chicks. I presume no-one else can get to the eggs before you? I say that because ours stopped laying until we put padlocks on the nest boxes then they started next day. Obviously a neighbour was stealing them. Now it is also a time when daylight hours become short and the temperatures drop so they physically can't eat enough whilst they are awake to both stay warm and make eggs. That may be a factor? Is the cage extension sheltered from wind and rain?