I did say it's a budget phone, Kev.
Using your thoughts, I've had another look and have the following:
1) Inside each post, and to the right of the post number & time posted, there is an empty square box. If I click it, it adds a white tick inside a blue background. No idea what that does.
2) At the top right there are three dots, which when clicked opens a VS box offering "Unsubscribe" "Refresh" and "Settings". The settings option offers thread sort order, online user sorting, Items per page, Theme, Font size, Attachment preview, and the Landing page of either Forms Index or Active Topics.
3) At the top left are three horizontal bars, which when clicked offer (under my user name) Forums index, Subscribed, Participated, Active topics, New posts, Private messages, Who's online, Sign out, and Exit Enhanced Mobile View. (Possibly the last one suggests that I already have the twiddly bits......but they aren't visible to me.)
4) At the bottom of my mobile there are no visible post options.
I've typed this on an old laptop to watch what happens when I click the mobile buttons, but no success yet.