The read byte, read bytes and timeout functions have been 'discovered' already. Highly recommended when conversing and talking to picaxe etc. For anyone interested the above port.readline() example works FAB with serial data arriving at the GPIO ad hoc / variable length and responds to the 13/10 LF/CR very nicely. I imagine it would be somewhere between the port command and the port.readline() command I imagine. Can someone indicate where and how such a clear buffer command would go in the above example so it runs once on startup.

If(rcv): print ('Serial # = ' + repr(rcv)) #Echo the buffer bytes back to screen #&c. While True: rcv = port.readline() #read buffer until cr/lf #if not null then. Import serial, time #this imports the libraries needed port = serial.Serial('/dev/ttyAMA0', baudrate=2400) #This sets up the serial port ttyAMA0 GPIO #baudrate is the bits per second. This can be time consuming / messy esp if processing and forwarding data off the UART as we are doing to a web server etc. When (re)starting the program the Pi seems to have happily accumulated everything and anything seen on the UART Rx line. Would be interested in how to clear the input serial buffer (and output?) as the following program example starts. Do specify a timeout when opening the serial port otherwise it could. dev/ttyUSB0 on GNU/Linux or COM3 on Windows. Port is a device name: depending on operating system. It is not opened when port is None and a successive call to open() is required. The port is immediately opened on object creation, when a port is given.

Python flush serial port buffer