The aim of the Blue Badge scheme is to help people with severe mobility problems caused by visible and non-visible disabilities (including anxiety disorders or a brain injury), to access goods and services by allowing them to park close to their destination. The scheme is linked to an individual, not a vehicle, so it can be used in any car, irrespective of whether they are travelling as a driver or as a passenger.
Within Buckinghamshire, the County Council is responsible for running the scheme, which provides a range of on-street parking concessions to Badge holders. It allows them to park without charge or time limit in otherwise restricted on-street parking environments (such as where there are meters and pay-and-display machines) and allows them to park on yellow lines for up to three hours, unless there is a ban on loading or unloading.
Be aware that, even when you have a Blue Badge, you might still have to pay for parking in a private car park, for example at a supermarket or hospital. Make sure you check the signs in the car park.