So, the contravention is defined in the legislation as follows:
"Subject to sub-paragraphs (2), (3) and (4), the yellow criss-cross marking provided for at item 25 of the sign table in Part 6 conveys the prohibition that a person must not cause a vehicle to enter the box junction so that the vehicle has to stop within the box junction due to the presence of stationary vehicles."
From the video, it seems that you entered the box junction and started to aim towards the vacant left hand lane but stopped because you were (rightly) wary of the vehicle approaching from behind you. Once the path was safe you moved into your intended exit lane on the left.
You may therefore be able to construct an argument that your stop was caused by moving vehicles (i.e. the one coming past you on the left) and that but for this vehicle (which was not stationary) you would not have stopped as you did.
It's not a guaranteed win as an adjudicator might argue you should have waited before entering as it was clear you would have to stop as you did not have the right of way.
There's also the PCN error I pointed out earlier. The London Local Authorities and Transport for London Act 2003 states:
"A penalty charge notice under this section must [my emphasis]—
(a)state—
(i)the grounds on which the council or, as the case may be, Transport for London believe that the penalty charge is payable with respect to the vehicle;
(ii)the amount of the penalty charge which is payable;
(iii)that the penalty charge must be paid before the end of the period of 28 days beginning with the date of the notice;
(iv)that if the penalty charge is paid before the end of the period of 14 days beginning with the date of the notice, the amount of the penalty charge will be reduced by the specified proportion;
(v)that, if the penalty charge is not paid before the end of the 28 day period, an increased charge may be payable;
(vi)the amount of the increased charge;
(vii)the address to which payment of the penalty charge must be sent; and
(viii)that the person on whom the notice is served may be entitled to make representations under paragraph 1 of Schedule 1 to this Act; and
(b)specify the form in which any such representations are to be made."
So, it is mandatory for the PCN to state that you may be entitled to make representations under the form specified in the Act (set out in paragraph 1 of Schedule 1).
Specifically, this section states (amongst other things):
"The enforcing authority may disregard any such representations which are received by them after the end of the period of 28 days beginning with the date on which the penalty charge notice in question was served."
Your PCN quotes the deadline after which your representations may be disregarded as "the period of 28 days beginning with the date of the notice of this Penalty Charge Notice". This is different to the date of service of the Penalty Charge Notice which is assumed to be 2 business days after posting.
As it incorrectly states information which it must state in order to comply with the Act, it could be argued to be invalid.
