By Andrew MacAskill and Kylie MacLellan LONDON (Reuters) – Boris Johnson said on Thursday he was resigning as Britain’s prime minister, bowing to calls from ministerial colleagues and lawmakers in his Conservative Party. Below is a summary of some of those who could be in the frame to replace him. There is no clear favourite and they are not listed in order of likely prospects. LIZ TRUSS The foreign secretary has been the darling of the ruling Conservative Party’s grassroots and has regularly topped polls of party members carried out by the website Conservative Home. Truss has a carefully cult…