I have spent a bit of time today trying to confirm or deny the link to the Peck family.
To being with the photo that appears to be the oldest, is one that shows the main featured woman when she was younger.
This is the best image I can find to compare the gentleman with Robert Peck. However, I am not very good at facial comparisons.
The next photo features wedding portraits from 1894 of Edith Peck and Harry Bates. The album contains a photo of a couple perhaps 10-15 years after the wedding portraits.
Another image shows Howbury Hall (06 September 1899 - The Sketch) shortly after the death of Robert Peck. What I have noticed with this photo is the ivy on the house. This does not appear on the photographs that I have. However, the ivy does appear in World War I era photographs of the property. At a guess the images I have might therefore be during the 1890s?
Roughly the Peck family lived at Howbury Hall from November/December 1889 until around January 1900, when the widowed Mrs Beck went to live at Pemberley House in Bedford. Between 1900 and around 1903 the hall was occupied by James E. Platt, and in around 1903 the Poilhill family returned to take up residence.
As JenB has pointed out, there is a certain interest in horses. Looking through the album there are a few photographs specifically of horses. Whether they are race horses or not, I do not know. However, the photo below is perhaps interesting. It is the only image to display any form of livery.
All of his sons became racehorse trainers, the eldest in 1911 being described as the horse trainer for the Earl of Durham. Perhaps the other mystery country house might be to do with the sons and their work.
This photo still remains a bit of a mystery as I have found no candidates for any of the people featured, as nobody who looks like they could be Robert Peck appears?
Still plenty of research to be done, but hopefully I am now heading in the right direction.