National Rail has confirmed that essential track and signalling upgrades between London Paddington and Heathrow/Reading will close several lines overnight from Monday 21 to Thursday 24 September. The works will reduce Elizabeth line frequencies to two trains per hour to Heathrow after 22:00 and suspend stops at Acton Main Line, West Ealing and Hanwell after 23:00. Great Western Railway (GWR) long-distance services will arrive in London several minutes late, and the 23:14 Paddington–Oxford will depart two minutes behind schedule. While the window is officially outside core business hours, the late-evening slots are heavily used by inbound business travellers and airline crews. Companies booking red-eye flights into Heathrow or scheduling client dinners in the West End should anticipate longer transfer times and limited seating. Heathrow Express remains unaffected but is likely to be busier and more expensive. Rail-replacement buses are not planned, so mobility teams should budget for taxi reimbursements where travellers face missed connections. The engineering is part of a wider £2.2 billion Great Western Upgrade aiming to raise line speeds ahead of the December timetable change. Employers should update traveller-facing apps and briefing notes to reflect the temporary timetable and consider flexible work-from-hotel policies for staff landing late. Passengers can check live schedules via the National Rail Journey Planner. Advance-purchase tickets may be changed without a fee if a service is cancelled; seat-specific reservations will not be enforced during the disruption period.
