Like everybody else, you would be acting (or not) based purely upon speculation. I would say that London is, generally speaking, immune from significant drops, due to constant demand for properties to rent and buy.
If you have no equity in the property, would renting it cover your mortgage? On that basis, you could live where you choose and the rental property would, based upon historical price trends, eventually glean an equity profit for you both
Just a thought
Good luck