Do not tell them and lie In theory most if not all do it to some extent. Thing is if it goes like I think it does for the 5 properties then I will be able to claim mileage back.....
I hear what some of you are saying ... but Underwriters aren't daft and do investigate the circumstances around claims. If they think you were using your bike for something you weren't covered for - they will throw the claim out. Sorry if this sounds dry and boring; but is the saving worth the risk?
When I worked for a law firm they paid the difference between my standard insurance and then the addition of use for business cover. Would bring it up with your new employer, they may do the same thing.