Donating quality used clothing

Are there any charities which take quality used clothes? My mother passed away last month and my sister and I have the sad task of sorting through her clothes. She was a very smart lady with clothes from place like Viyella and Jacques Vert, some hardly worn. She also has a lot of hats. I don't want to donate to a local shop as I couldn't bear to see someone wearing her things,but I'd be willing to take them further away. She would want them to go to a good cause though and I know she supported Cancer Research UK and our local hospice and air ambulance. Any ideas gratefully received.