According to Mick there was a late submission. this could be either the return, which would result in an assessment if left a while, or the payment, which would not result in an assessment. either of these would result in a surcharge if it was the second occasion.
the assessment for the late return is easy to deal with: you put in the return, and HMRC alter their expectations accordingly, to the amount due on the return.
The surcharge however is a different beast: you could be a day late, and yet be assessed for a surcharge of £250k (an example quoted by tax consultants). You can either ask for a review by HMRC or appeal to a tribunal. However the communication between the department in Newcastle that the review/appeal request/notice is sent to and the debt collection service are pretty bad, so I am not surprised at all that the debt collection dept got itchy fingers and pressed the petition button without consulting their colleagues
The government back in about 2010 recognised how unfair it was that the same surcharge was applied irrespective of whether you were a day or a year late, and suggested a move to greater proportionality, however HMRC have been too busy to work out a fairer system (yes FA I know what you are going to say, HMRC get commission on it so of course they are too busy, counting their bonuses!).
This happened 3 months ago, and it sounds to me like a surcharge, HMRC will fight the appeal so that other companies are not given the opportunity to use the same basis, and it could simply be one day late.
so they know what the worst is, and I am sure that Marc and Steve will have planned for the eventuality of the appeal failing,
