Hello Rob and Henrik

Thanks for your replies. old Murphy’s Law is still alive and well..! No sooner had I posted my thread I discovered my fault. Rob you are right on the money, I clean forgot that all the clocks on the processor are disabled while it is in sleep. Reading through the documentation, on the UART, I read that BAUDCON.1 allows the RX pin to operate as a change state interrupt and just assumed that the processor would wake up on the mark and would be alive and ready to read the data on the RX pin. Clearly this was not the case, I had not accounted for the oscillator start up time.

Thanks for your input, I should have sent my post earlier, I would have got the help I needed sooner