That certainly was historically the case, and I have little doubt they will have barred windows, but the SA, at least as currently published on-line, doesn't actually say that.
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What it actually says is
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MARYPORT To Carlisle South Jn
Restricted clearances exist between certain trains and infrastructure on this section of line. The operation of a
Departmental or passenger train movement that includes within the formation any former passenger carrying vehicles with
drop light windows (including Mark 2 air conditioned vehicles), requiring to operate between Maryport and Carlisle (in
either direction), is authorised to proceed subject to the timely and formal issue of a Special Notice to all parties that
MUST include the following:
The Person in Charge of the train must ensure that all droplight windows are closed and that they remain
closed.
The Person in Charge of the train must also ensure that the persons occupying the vehicles have been advised
not to lean out or extend anything out of any window.
In connection with the operation of a train comprised of Mark 2 air conditioned vehicles, the organiser must
arrange for Stewards to be positioned at each door of every vehicle to enforce the restriction.
The Person in Charge of the train must brief everyone on board, including the Train Crew, to ensure these
instructions are adhered to.
Compliance to the above especially amends Table D3 Route clearance of coaching stock as published in Module
NWRC of the LNW(N) Sectional Appendix.
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The reference to table D3 is that it shows mk.2s as only permitted ECS.
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