Original: Like virtually all Underground lines, the Piccadilly line is operated by a single type of rolling stock, in this case the 1973 tube stock, in the standard London Underground livery of blue, white and red.
Simplified: The Piccadilly Line is run by the 1973 tube stock, in the London Underground colours of blue, white and red. The line was run by 1959 stock, 1956 stock, 1938 stock, standard tube stock and 1906 gate stock, before they were replaced by th 1973 stock.