Two condoms found inside a 16th century medical manual have gone on display at Salamanca University's General History Library.

Made from pork tripe and with a blue string at the open end to minimise spillage, they were actually found inside a newspaper dating from 1857, and probably left behind by a medical student.

While there is evidence that condoms were used by both the Romans and Egyptians, they were not officially invented until the 16th century by Italian surgeon, Gabriele Fallopio.

The following century Count Condom, the personal physician of King Charles II of England, perfected Fallopio's preservative using stretched pork intestine lubricated with oil.