There are a few exceptions within England. For example, the charter of the University of Manchester provides for the vice-chancellor to also use the title "president", and the first vice-chancellor, Alan Gilbert (2004–10), used "president" as his main title. The University of Warwick now officially uses "vice-chancellor and president" (VCP), although the holder is usually still known as the vice-chancellor in all but official documents. The chief executives of the constituent colleges of the University of London, many of which are now functionally independent universities, generally use the title "principal", although the chief executive of Imperial College has the title "rector", the London School of Economics' head is titled "director" and Birkbeck College is headed by the "master."