http://www.uk-wp.com/2011/12/06/ukba...om-march-2012/

In addition, once Indefinite Leave to Remain becomes a ‘Biometric’ application, applicants will no longer be issued with a sticker in their passport showing their new ILR status. They will instead receive a separate Biometric Residence Permit (BRP), which is a credit card sized ID card. There will no longer be any indication in the person’s passport of their status in the UK. This means that the individual will need to present their passport and their BRP card together whenever they are required to prove they have a valid visa – at the border or to a potential employer, for example. If the applicant loses their BRP card, an application must be made for a replacement, which incurs a further cost.