Sefton Church is in Liverpool and the original part of the building was constructed in the 12th century, with additions made during the 16th century.
The photo was taken in 1999 and only the person and another photographer was in the church at the time the photo was taken. There is a school of thought that this figure could be an previous minister, who served at the church.
An interesting point to add is that there are 16 military war graves (WWI and II) in the church yard. To me eye, this figure looks like they are a soldier due to the fact the figure is wearing a pair of puttees- the fabric being wound around their lower half of their legs.
Another interesting point is this church is next door to a pub, called The Punch Bowl, where a ghost wearing nautical clothing is said to have been spotted many times.