LONDON (Reuters) -Britain set out a plan on Wednesday to stop P&O Ferries benefiting from its decision to fire workers and replace them with cheaper agency staff, saying ports should refuse access to ferry services that do not pay the minimum wage. Transport minister Grant Shapps said Britain would introduce new laws, strengthen employment rights and close legal loopholes as part of a package of measures to prevent a repeat of P&O’s decision to make 800 staff redundant without notice and hire cheap alternatives. Shapps said if ports refused access to P&O unless they paid staff minimum wage, it…