CIPFA have published their latest report on Brent libraries. You can follow the link here. "Latest" is something of a misnomer, as they always publish their reports a year out of date. If you want the most recent figures you can find them here.
If you haven't seen them before, each report analyses a group of Boroughs that CIPFA regard as compatible. In the case of Brent that is a series of outer London Boroughs.
Brent is now in the top quartile for physical visits, and in the middle in terms of book issues. I was surprised to find that book stock is towards the lower end of the group, although the books are borrowed more frequently than average. I don't know how they reconcile Brent's access to the rest of the London Lending Consortium book stock. Perhaps the most worrying factor is the low proportion of active borrowers relative to population