It's a difficult one. They territorials did go at some respectable ages. Here's an example of one in the
1/5th Northumberland Fusiliers.
But as you say it's more likley to be the younger one.
The Western Front Association have obtained a
new series of documents that might help if a pension claim was made but I assume they won't be available for a while. I'm looking forward to seeing/using them anyway.