I have changed the horizontal oxygen sensor which was easy enough and it turns out I should have changed the the vertical one! Ahhh. Anyway, the sensor is easy enough to loosen and I've been able to lift the tank and follw the route of the wire. However, I'm a little perplexed as to how I drop/lift this part of the bike to enable the connector or the sensor to pass through!!
Sussed it. You have to remove/undo the heat shield and the rear subframe to lift it out of the way!! Easy then!