Artists and illustrators young and old joined together in Oxford today to launch the world's biggest drawing festival.

Children's Laureate, writer and illustrator Chris Riddell and author Philip Pullman were guests of honour to open The Big Draw at the Bodleian's Weston Library in Broad Street.

The pair opened the festival with an illustration demonstration where Mr Pullman read an extract from his Grimm Tales while Mr Riddell illustrated.

The hall was filled with families for the opening presentation, where there where a series of events activities were being staged.

Artist Patrick Tresset set up his sketching robot Paul III, which uses a camera and robotic arms connected to a laptop to create portraits.

Youngsters could also draw cityscapes with a Camera Obscura then turn them into prints in the library, or draw parts of the Sheldon Tapestry then hang them in a web to create a 3D map.

There was also a Drawing Together visitor book, a massive scroll of paper on which guests young and old were encouraged to leave their mark.

Events are going on throughout the day at the library and around the city until 4.30pm, with other drawing-themed activities planned for the rest of September and into October.

Visit thebigdraw.org