Thanks so much, that's exactly what was needed. I've been peering up into the boiler for the past few hours trying to find a hole for the key!!
Thanks again
I've recently bled my radiators and since then have lost all pressure on the boiler. I've read all the other posts about needing to re-pressure the boiler with a plastic key but i am not even able to find the pipe/valve to do this..
This is the post for someone with a similar problem but i...