@yimkc this can be appealed on various grounds, including the situation being an emergency and it being doubtful whether you were parked on a borough road. However the trump card is the date of the PCN, which is 6 April 2024 i.e. a Saturday. I have an FOI from TFL (I can forward it to you) confirming that they do not have postal collections on a Saturday, however paragraph 3(1)(a) of Schedule 2 to The Civil Enforcement of Road Traffic Contraventions (Approved Devices, Charging Guidelines and General Provisions) (England) Regulations 2022 provides that:
3.—(1) The information to be included in a regulation 10 penalty charge notice is—(a) the date of the notice, which must be the date on which it is posted,
This has won previously, see these cases:
Cristina Cornea v Transport for London (2230309290, 24 July 2023) (https://drive.google.com/file/d/1z-7nXLFc-FUU2A5MEZqnT_r6VvL1EpD6/view)
Martin Tony Arlington v Transport for London (2230244402, 23 August 2023) (https://drive.google.com/file/d/1Pa3c_Vk4mwWbR0S93ZUgq1wC48TEAZwP/view)
@yimkc the traffic order is The GLA Roads and GLA Side Roads (Westminster) Red Route Consolidation Traffic Order 2008 (https://drive.google.com/file/d/1LOnrlNq-ehg8kH2cmAGnTq2Dj6Dqe3VO/view).
However what is more interesting here is The GLA Side Roads (City of Westminster) Designation Order 2008 (https://drive.google.com/file/d/12qp6xLdgGA4fwUTDucHIorHgZ3P8iJt6/view) which has this entry on page 5:
CHAPEL STREET the south side between its junction with Edgware Road (A5) and the extended common boundary of Nos. 15 to 16 Hyde Park Mansions, Cabbell Street and Nos. 256 Edgware Road
You can see number 256 Edgware Road here on the right: https://maps.app.goo.gl/GKYWRo2Y6SARYR7A6
So it is arguable that you were not stopped on a GLA side road but rather on a borough road, so the enforcement authority is the City of Westminster, and Transport for London has no powers to enforce at this location.
I see you submitted a representation already, please can you show us exactly what you sent?