Ten years after the Brexit referendum, a growing number of people in Britain are questioning the UK's  departure from the EU. The activist Ceira Casey Sergeant is marching from London to Brussels to campaign for rejoining the European Union. Critics of Brexit cite weaker economic growth and pressure on the National Health Service. Some people who supported Brexit now say key promises made by "Leave" campaigners were never made good on. As public opinion shifts, over 80% of people younger than under-25s are said to support a return to the European Union,  fueling a renewed debate about Britain's future relationship with the EU.