Further tests have now been completed by the pathologist who has given a result of carbon monoxide intoxication.
A petrol-driven pump was seized from inside the home address at the time of Zane's death and Surrey Police is conducting further inquiries to establish whether there is any liability or criminal offences in respect of the hire company who provided this equipment.
More top news
The London property market is expected to be the hardest hit as buyers sit it out to see how the economy will be affected.
The former London mayor paid tribute to David Cameron just hours after the Prime Minister announced his resignation.
The pound crashed to its lowest level in 30 years as Britain voted to leave the EU.