The Vampires of Cymru — Philip R Benge

For 1500 years, four vampires lay trapped beneath the ground in a torture chamber built especially for them, only to be released in the year 2019 when the foundations of a new office block were dug. Freed, the vampires begin where they had left off, draining the blood of more innocent victims. Professor Myrddin, his friend Father Mason and four students must fight them or see even more people killed, or even worse, be turned in to vampires.