Hello Pompey,
yes, they do need time to settle, relax and feel secure.
Mine are about 48 weeks old and produce an egg a day each. They are 5 Blacktails, 3 utility Leghorns and two hybrid Sussex, one white, one dark speckled. They seem happy contented girls. Produced all over the winter to the delight of my family and friends.
Yours will too, but sometimes it seems to take forever.
My hybrid green egg layer Cream legbar/Leghorn cross also took forever, but unfailingly now produces a green egg a day. Be patient.