Error: Strict Standards: Declaration of format_topcoll_rendererRror

We have recently upgraded our Moodle 2.3.1 test site to the latest 2.4.3

A large number of courses in the test site fail to display anything except the following error message (with debug on)

Strict Standards: Declaration of format_topcoll_renderer::section_header() should be compatible with that of format_section_renderer_base::section_header() in C:\inetpub\wwwroot\course\format\topcoll\renderer.php on line 37 Fatal error: Cannot override final method format_section_renderer_base::is_section_current() in C:\inetpub\wwwroot\course\format\topcoll\renderer.php on line 37

Strict Standards: Declaration of format_topcoll_renderer::section_header() should be compatible with that of format_section_renderer_base::section_header() in C:\inetpub\wwwroot\course\format\topcoll\renderer.php on line 37 Fatal error: Cannot override final method format_section_renderer_base::is_section_current() in C:\inetpub\wwwroot\course\format\topcoll\renderer.php on line 37

There isn't any obvious pattern for which courses display and whcih ones don't. It occurs in all browsers.

Any suggestions on how to resolve would be welcome.

Phil