Hi Andy,
I think you might not be seeing what is happening on the receiving end. Should you be receiving the data with an IBM compatible computer using Procomm software set up with the below patterns it would process the data as 7 data bits and ignore the parity bit.
1 start, 7 data bits, odd parity, 1 stop bit
1 start, 7 data bits, even parity, 1 stop bit
1 start, 7 data bits, Mark parity, 1 stop bit
1 start, 7 data bits, Space parity, 1 stop bit
Regards,
Charles Bannister