Banned from parking in business park

I work on a business park which is running short of parking spaces and has no bike spaces at all so I use a car parking space.

I am being told that they are going to ban motorbikes from parking in the business parks with a £100 fine. Is this legal?

As a relatively new biker do we really have to deal with such discrimination? I pay my road tax and only expect the same rights as a car. If I went to work in the car I would only take the same space!