Thanks for your replies and suggestions. I've looked at them all and in the end came up with a hybrid solution based partly on gandalf458's approach and the menu setup used by coothead which I found by following the link suggested by SamA74. Because I use folders I ran into some issues that don't turn up if everything is in one folder.
I placed the following in my common header, called by all pages:
$page = basename($_SERVER['PHP_SELF']);
Here are a few lines from my main menu which is in a php file called by all pages:
<ul id="menu" class="nav nav-stacked">
<li <?php if ($page == 'bod_current.htm') echo ' class="disabled"'; ?>><a href="https://www.hkvca.ca/bod/documents/bod/bod_current.htm">Executive List</a></li>
The menu php file contains two menus - one is site-wide, the one below it contains links to the "home" page in each folder. I had to give each "home" page a unique name, however. It works fine, although I had to go for absolute links in the site-wide menu (which is OK because they will hardly ever change).
So, thanks to you I've learned a lot, and have solved my problem.
All the best,