Calderbank is not dead. Its still around for all court cases that started before the new rules on costs!
Such as ours, where it started in 2004 and has dragged on and on and on ZzzzzzzzzzzzzzzzzzzzzZZZzzzzzzzzzzzzzzzz Her Solicitors threaten us with costs with every letter they send. Sometimes 11 letters in 14 days! Nice if you can afford it hey!
Perhaps I should have said that according to my sol Calderbank was dead unless one had been issued before the deadline. However, she doesn't fill me with confidence, so there is a good chance she is wrong and that they are still usable where the case has started.
Seems then that Calderbank is not dead as the corpse is still twitching.
If your ancillary relief proceedings commenced after that date then the new cost rules apply (i.e. open offer letters and a presumption that each side covers their own costs as long as everyone is playing fair)