"The earliest rendition or inclusion (on screen) of discernible 'Escape Hatches' were on the Ambassador Class Enterprise captained by Rachael Garret in 'Yesterday's Enterprise'."
As the designer of the original and beautiful Ambassador Class Enterprise (Enterprise-C depicted on conference room wall sculpture display) I would not expect Mr. Probert to pay any
attention to a design that pushed his original design over the cliff.
To illustrate the issue check out Tobias Richter's amazing and fully operational CGI recreation of Mr. Probert's original design:
As an afterthought I just had a discussion with one of my friends regarding the lifeboat issue. He wondered if it really would make sense to have the necessity of a hatch opening (mechanical failure?) and felt it to be more sensical that what appears to be a hatch panel is actually one side of the lifeboat.