Anniversary Ghosts

Many hauntings are rumoured to be anniversary ghosts, where the strange experiences associated to a case are repeated at regular intervals, usually once a year on a set date. What are your favourite anniversary ghosts and what are the best ways to investigate them?

Here's one I copied from the Cumbria section

A phantom army was witnessed on Souther Fell by a farm hand on Mid-Summers-Eve in the year 1735. The army took the form of mounted troops with infantry marching in a column. One year later on the same date the army was seen again by William Lancaster who was a local farmer. In 1745, the year of the Jacobite uprising the army was witnessed again by over 26 people on the 23rd June. This time the army was sighted with carriages, and covered an area of about half a mile. It would not have been possible to bring carriages on Souther Fell and the story is a complete mystery. An account of the haunting appeared in The Gentleman's Magazine in 1747.

These are said to be anniversary ghosts that appear on Halloween.

Minsden Chapel, Hertfordshire
At Minsden Chapel in Hertfordshire the ghost of a monk is said to walk through the ruined arch, heralded by the peel of a bell. http://www.mysteriousbritain.co.uk/hauntings/minsden.html

Newton Castle, Perthshire
The apparition of the Green Lady of Newton Castle is said to be most likely to appear at Halloween, her gravestone is also meant to turn around three times. http://www.mysteriousbritain.co.uk/scotland/perthshire/newton.html

Armboth House and Thirlmere Lake, Cumbria
Armboth House was haunted following the drowning of the household's daughter on Halloween, the night before her wedding day. The house now lies submerged beneath Thirlmere resevoir, but it is said that the sound of bells can still be heard, and a ghostly dog is said to swim in Thirlmere Lake (where she was murdered).

Cliviger Gorge, Lancashire
A ghostly huntsman and his hound are said to appear.