Answering my own question here:-there is a small slot at the side of the switch button - you have to insert a small flat blade down here to release the catch to remove the button.Once removed there is torx screw which releases the whole assembly (slides up) including the input cable.Got the answer from letsfixit.com - including links to the spares you may need when you try removal without this knowledge
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix vacuum cleaners.