A rare document signed by one of William Shakespeare's most important patrons was sold at auction for £250 yesterday.

The document, dated 1608 and signed by William Herbert, 3rd Earl of Pembroke, was auctioned in Ludlow, Shropshire.

The First Folio of Shakespeare's plays is dedicated to Pembroke and many scholars believe he is also the mysterious "Mr WH", dedicatee of the writer's sonnets. The document was an important legal transaction involving the sale of two manors in Somerset to John Still, Bishop of Bath and Wells.

It was signed by Pembroke and includes a long list of tenants of the manors, which cover the area around what is now Burnham-on-Sea.

Document expert Richard Westwood-Brookes, from Mullock Madeley auctioneers, said: "There was a fair amount of interest in the document. It was sold to an anonymous buyer from Somerset, which is nice because of the document's links to the area."

He added: "It is fascinating to think that the person who signed this document knew Shakespeare personally, and can be seen as one of the most important figures in the development of his plays.

"Documents signed by important figures in Elizabethan England are becoming increasingly rare on the market, and particularly so if they are signed by anyone associated with Shakespeare, so we are expecting considerable interest."

Herbert was an important literary figure of the late 16th and early 17th centuries.

His father formed a company of players, known as Pembroke's Men, which exclusively performed several of Shakespeare's plays.

When his father died in 1601 Pembroke continued patronage of the stage and supported Shakespeare and another major playwright of his time, Ben Jonson.