I have changed back the group to root for jackd. However, if I launch jackd and rosegarden as user the same error occurs - rosegarden does not believe that jackd is running. I can only stop the error occuring by running rosegarden as root. This is why I think it is a permissions issue. If this is the case I am not sure what needs to be changed?
Sorry, my ignorance regarding the virtual keyboard. I have not used rosegarden before, indeed I haven't used any midi sequencer for many years. The matrix editor looks like what I was looking for and will do the job fine for now until I get the rest of the kit sorted out.