Willington Augustus David Shelton born 21st May 1849 Co. Limerick was the son of Jonathon Robert Willington Shelton and Emily Hills.Jonathon Robert W. Shelton was the son of John Willington Shelton and Mary Richards and a nephew of Susan Shelton, wife of James Walter Agar. (John Willington and Susan being brother and sister).
That would make Willington Augustus David Shelton a second cousin of Augustus Willington Agar.
If I can be of any further help, please dont hesitate to contact me directly.Do you have any info an the Agar side?