Fire near Harrow-on-the-Hill halts Marylebone-Amersham line until midday

All lines towards Aylesbury via Amersham are disrupted this morning after a fire broke out at a property near the railway between London Marylebone and Harrow-on-the-Hill, according to [1]. National Rail says no trains are running between Marylebone and Amersham, with the disruption expected to last until approximately 12:00 [1]. The knock-on effect reaches well beyond that stretch of track. Chiltern Railways, which operates the route, has cancelled or revised services across its network, with routes to West Ruislip, High Wycombe, Aylesbury, Aylesbury Parkway, Oxford, Birmingham Moor Street and Birmingham Snow Hill all affected, according to [1]. To keep some services moving, Chiltern is running an hourly train from Marylebone to Aylesbury via High Wycombe, avoiding the fire site, alongside a separate hourly shuttle between Aylesbury and Amersham, according to [1]. Passengers holding tickets for the affected routes can use them without extra charge on a wide range of alternative operators and lines while the fire disruption continues, according to [1]. These include Avanti West Coast between Euston and Milton Keynes Central or Birmingham New Street; CrossCountry between Reading and Oxford, Banbury, Leamington Spa or Birmingham New Street; Elizabeth line services into central London, Paddington and Reading; Great Western Railway between Paddington and Reading, Oxford or Banbury; and London Northwestern Railway between Euston and Tring, Milton Keynes Central, Coventry or Birmingham New Street, according to [1]. On the Underground, the Bakerloo line is available between Oxford Circus, Paddington and Marylebone, and the Central line between West Ruislip, South Ruislip and Oxford Circus, according to [1]. The Metropolitan line is running trains between Harrow-on-the-Hill and Amersham, though National Rail notes both the Metropolitan and Jubilee lines are closed beyond the area affected by the incident, according to [1]. Bus services S4, S5, 2 and 2A covering Oxford, Oxford Parkway, Banbury and Bicester are also valid for ticket use, according to [1]. National Rail says passengers may be entitled to compensation for delays and advises keeping tickets and a note of the journey to support any claim, according to [1]. The fire disruption follows a separate, unconnected episode of Chiltern line trouble reported previously: an evening safety inspection of track between West Ruislip and South Ruislip that blocked the line towards Marylebone and caused cancellations and delays of up to 45 minutes, according to [2]. That inspection came in the wake of two passenger train derailments outside London within 24 hours of one another, amid a heatwave with temperatures above 38C, according to [2]. The Rail Accident Investigation Branch and Network Rail were investigating those derailments, with extreme heat-related rail buckling cited as a known risk factor, according to [2]. It is not established in the material whether today's fire-related closure has any connection to that earlier heat-related inspection or the derailment investigations; the two incidents are reported separately in the source material. What to watch next: whether Chiltern's 12:00 target for restoring the Marylebone–Amersham line holds, and whether National Rail issues any update tying today's fire disruption to the ongoing derailment investigations from last week.