By Iain Withers and Carolyn Cohn LONDON (Reuters) – Major British financial companies collectively narrowed their gender pay gaps last year, but some went into reverse gear, including UBS and Deutsche Bank, a Reuters analysis found. Companies in Britain with more than 250 employees have been required to publish the difference between the pay and bonuses of their male and female employees since 2017. They had an April 4 deadline this year for disclosures up to April 2021. Several financial companies this year also published voluntary ethnicity pay data – some, including UBS, Aviva and M&G, for …