I think you might be referring to FMC WPR (FMC Waypoint Reporting) which will send a position report based on FMC data to ATC. Should you select abeam points in your FMC with a 'direct to' clearance, then these abeam waypoints will be transmitted to ATC as part of the position report.
This really only applies to more remote areas such as the North Atlantic and not the UK. This is one reason why ETOPS Equal Time Points should not be entered into the FMC flight plan as it will confuse ATC.