The commission in charge of mounting the Great Exhibition was established in January 1850, and it was decided at the outset that the entire project would be funded by public subscription. An executive Building Committee was quickly formed to oversee the design and construction of the exhibition building, comprising accomplished engineers Isambard Kingdom Brunel and Robert Stephenson, renowned architects Charles Barry and Thomas Leverton Donaldson, the Duke of Buccleuch and the Earl of Ellesmere, and chaired by William Cubitt. By 15 March 1850 they were ready to invite submissions, which had to conform to several key specifications: the building had to be temporary, simple, as cheap as possible, and economical to build within the short time remaining before the Exhibition opening, which had already been scheduled for 1 May 1851.