No change in policy, no bags in the exit rows, or the seat in front of an exit row, nor at the bulkheads, during taxi, take off and landing. In your lap you are only allowed smaller items that you can fully secure, such as a mobile phone or a book, but not laptops, coats and other clothing. During the flight is fine, unless there is a bad turbulence event coming up, when it's back to full securisation. Usually BA crew are pretty good at spotting those dark handbags hidden down the side of the front seat, but once in a while the crew may not notice or not realise they are passing the exit row. One failed capture is not necessarily the end of the world, mostly aircraft don't crash on the whole, but it shouldn't happen.