There are two sub-classes of a Bridging visa D:
This visa is for applicants who are unlawful / illegal (or will become unlawful within 3 working days) and wished to make a substantive application but has been unable to do so for reasons beyond their control.
In these cases a Bridging Visa D is granted for 5 working days to allow a valid application to be made onshore for another substantive visa.
This visa is for an unlawful non-citizen unable to or not intending to make a substantive application and an authorised officer is not available to interview them for the purpose of considering their eligibility for a Bridging Visa E.
Bridging Visa Other Classes