Current and former MPs will give evidence at the Grenfell Tower inquiry amid union calls for politicians to be held to account.Northern Ireland Secretary Brandon Lewis will on Wednesday be the first politician appear as a witness at the inquiry, which is attended by bereaved family members and survivors of the 2017 blaze.Mr Lewis was a minister with responsibility for fire safety from 2016 to 2017.Stephen Williams, Lord Wharton and Gavin Barwell, all of whom were ministers with responsibility for building regulations in the run up to the disaster, will also appear, and former fire safety minister Lord Pickles.Matt Wrack,...