Is My Boy's Home Big Enough?

Having only recently learned 'a hutch isn't enough', I've been actively taking steps to give my wee boy more space. I think he is quite happy with it, but now I feel I'm about to be 'put to the test' because I have a home visit from the rescue centre scheduled for next week in regards to rehoming a second rabbit.

Chewy (a mini lop) has a 100cm indoor hutch which opens into a 4.5'x4.5' run. This is his space during the day when we are out and about, and at night while we sleep. When we are in, he has access to the whole lounge - a rather big lounge for a flat, but no other room in the house.

Is this enough? Will it be enough for a second bunny to join him in?

I think that so long as you can emphasise that the majority of the time he has free range space, it should be fine hun.

That's not too bad a size, if he gets free-range time too. I assume the cage is not in the pen, but added onto the side of it?