I have tracked down the cause of this by looking at the plans in the database table; the hideregistrationfields column has data in it as a result of importing the plans table from an earlier joomla site in which the numbers represented different fields; having cleared this field for those plans affected I now have the captcha displaying. so my fault for trying to save time and ending up wasting yours as well as mine - sorry and thanks for your help
Last edit: 6 years 8 months ago by Thelowlandpiper.