Chiltern are slashing services to just 4tph ex-Marylebone from Monday, rather than the usual 10 off-peak. Full details at
https://www.chilternrailways.co.uk/coronavirus but to summarise:
- 1tph Marylebone - Aylesbury Vale Parkway via Amersham
- 1tph Marylebone - Aylesbury via High Wycombe calling all stations except the Sudburys
- 1tph Marylebone - High Wycombe - Princes Risborough - Haddenham & Thame Parkway - Bicester North - Banbury - Leamington Spa - Warwick - Warwick Parkway - Dorridge - Solihull - Birmingham Moor Street
- 1tph Marylebone - Gerrards Cross - Beaconsfield - High Wycombe - Haddenham & Thame Parkway - Bicester Village - Oxford Parkway - Oxford
- 1tp2h Leamington Spa - Warwick - Hatton - Claverdon (SuX) - Bearley (SuX) - Wilmcote - Stratford-upon-Avon Parkway - Stratford-upon-Avon
Kings Sutton, Hatton, Lapworth and Islip to get a call every 2 to 3 hours to/from London.
During peak times Monday to Friday, an additional two trains per hour will run:
- 1tph Marylebone - Wembley Stadium - Sudbury & Harrow Road - Sudbury Hill Harrow - South Ruislip - Denham - Gerrards Cross - Beaconsfield - High Wycombe
- 1tph Marylebone - Aylesbury via Amersham
No trains will run beyond Birmingham Moor Street for the duration, so I'd assume there won't be any loco-hauled services.
NB: As per the base timetable, Sudbury & Harrow Road will only be served Southbound in the morning peak and Northbound in the evening peak.