DWP-held information

Can anyone remind me of the case citation for the (UT?) decision which said that if DWP holds information relevant to a decision it should check its own records rather than expecting the claimant to provide it? Was it part of the takeaway from MW (IS)? I am doing an MR of a decision to stop IS after the DWP failed to record a change of address notified by my client and correspondence was sent to the old address (they say they tried to call her, but they had also incorrectly recorded her mobile number); DLA and CA remained in payment as the basis for IS entitlement and her change of address was correctly recorded by those sections. We have made an SAR but it will be quicker and easier for all concerned if the DWP checks their own information.

OK, found it - it’s Kerr.

Also a general public law duty to use that which is already available to you.