Thanks to those of you who, having been unable to post comments on my blog, reported this to the Blogger Help forum.
The latest response is as follows:-
Sounds like the individual followers have browser issues of their own that are not related to your blog specifically. They'll need to write a post on this forum as a new topic.
This is the link to the page concerned.
I'm sorry this has happened, but it would seem that it is absolutely nothing I can do about it. Obviously some followers are able to comment which would indicate that the problem isn't with my blog.
Let's hope your individual issues can be resolved soon and I can welcome you back!