Hidden disabilities are very prevalent – the rather lazy depiction of a wheelchair or guide dog to summarise people with additional access requirements does a disservice to the many more who are not easily visible, but still require consideration from service providers.
Gatwick Airport has recently introduced a scheme whereby travellers can request a lanyard to wear around their neck, signalling to staff that they have a hidden disability and may need extra help. The scheme has also been accompanied by an increase in training and disability awareness for staff, and judging by comments made in the Independent Living Facebook Group, I would say that the training gets more of a thumbs-up than the lanyard! You can read more here