Links menu missing from admin panel and no link widget in child site

I’ve just configured a multisite installation from an existing single site installation. Mostly it seems to have gone fine – the existing site still works just as it did and I have set up a new child site that is almost working properly.

But in the child site I have no ‘Links’ section in the admin menu and no Links widget. I am logging in to both sites as the same user – the Superadmin user. I am using the same theme on both sites (a child of twenty twelve) and have also tried switching to stock twenty thirteen on the child site to see if this enables the Links menu, but no joy. I’ve even tried adding code to the theme’s functions.php to add the manage_links cap the author or administrator role.

Plugins enabled on the child site at the moment are Add Meta Tags, Jetpack, TinyMCE Advanced and WP-footnotes