Please answer the following question: Vaughan Williams gave an introductory talk before the performance of what work at The Old Vic?  Answer the above question based on the context below:  In June 1911 Holst and his Morley College students gave the first performance since the seventeenth century of Purcell's The Fairy-Queen. The full score had been lost soon after Purcell's death in 1695, and had only recently been found. Twenty-eight Morley students copied out the complete vocal and orchestral parts. There were 1,500 pages of music and it took the students almost eighteen months to copy them out in their spare time. A concert performance of the work was given at The Old Vic, preceded by an introductory talk by Vaughan Williams. The Times praised Holst and his forces for "a most interesting and artistic performance of this very important work".After this success, Holst was disappointed the following year by the lukewarm reception of his choral work The Cloud Messenger. He again went travelling, accepting an invitation from H. Balfour Gardiner to join him and the brothers Clifford and Arnold Bax in Spain. During this holiday Clifford Bax introduced Holst to astrology, an interest that later inspired his suite The Planets. Holst cast his friends' horoscopes for the rest of his life and referred to astrology as his "pet vice".In 1913, St Paul's Girls' School opened a new music wing, and Holst composed St Paul's Suite for the occasion. The new building contained a sound-proof room, handsomely equipped, where he could work undisturbed. Holst and his family moved to a house in Brook Green, very close to the school. For the previous six years they had lived in a pretty house overlooking the Thames at Barnes, but the river air, frequently foggy, affected his breathing. For use at weekends and during school holidays, Holst and his wife bought a cottage in Thaxted, Essex, surrounded by mediaeval buildings and ample rambling opportunities. In 1917 they moved to a house in the centre of the town, where they stayed until 1925.
A:
The Fairy-Queen