Much as I like the Metcalfe kits, I dislike the chimneys that are supplied with them. I just don’t think rolled up card looks right. Also they are unbelievably fragile and get knocked off at the first opportunity.
Fortunately Langley can supply Cast chimneys and even better can supply them ready painted. As they come on a sprue, cutting them off leaves a useful tail so drilling a 1mm hole in the top of each chimney allows each pot to be stuck firmly in place.