I think I've found my problem. It concerns the "enablePooling" init-parm of the org.apache.jasper.servlet.JspServlet. I have changed the init-parm in my jboss-3.2.5\server\default\deploy\jbossweb-tomcat50.sar\web.xml file but the apache instance in JBoss still appears to be pooling the Tags.
Silly Me. I needed to delete the compiled JSPs. All good now. Thanks for all your help