I agree with Jim that the 1924 date and her at 25 is on the money. Good photo with the clean up, and I also agree she doesn't look too old, a lovely photo. In the second photo, the little girl likewise looks the age of two in 1931, Fathers little girl, and a sad passing.
Very difficult to make out the background hence park location, but I remember quite a few parks on that long street, with hotels behind.
I hope I am not being too inquisitive, but was your Grandfather in the Hotel Trade, thinking with the above, he might have been taking a break in a park opposite the Hotel. If so he probably had accommodation provided, but obviously pure speculation.