These effigies are on the tombs of well-to-do lay-folk from the early 15th century. As a medievalist, I have a particular fascination with art, sculpture and literature from this period and actually wrote my Masters dissertation about iconography associated with death and funerals from this time. Macabre and morbid, you may think, but undoubtedly fascinating.
We can learn a lot about the religious practice and beliefs of people at this time, from how they handled death. It was only in the 14th century that recumbent effigies on tombs such as this, began to show the deceased with their hands clasped in prayer. Around this time, the Ars Moriendi (The Art of Dying) was written and began to be disseminated widely, guiding lay-people how to 'die well'. The text describes the five temptations that dying people face - loss of faith, despair, impatience, vanity and greed - and the five solutions to these temptations: faith, hope, patience, humility and generosity.
It would seem that the effigies commissioned for the tombs of wealthy people were sculpted in such a way as to show the deceased as 'dying well', clasping their hands together in a show of faith.