How to get Jetpack working

When I click connect to wordpress from jetpack

I get

Invalid request, please go back and try again.
Error Code: invalid_request
Error Message: Mismatch in redirect_uri.

URl looks like

https://jetpack.wordpress.com/jetpack.authorize/1/?response_type=code&client_id=30263140&redirect_uri=http%3A%2F%2Fwww.mungreteng.com%2Fwp-admin%2Fadmin.php%3Fpage%3Djetpack%26action%3Dauthorize%26_wpnonce%3D797632b933&state=1&scope=administrator%3Ab215cf286dae6619470a8d45b2552630&user_email=ronandownes%40gmail.com

Ronan