No that this matters, but I am an Arsenal fan who attended the game, and I am still leaning towards penalty. I agree with Monotone Whistle that I probably would have awarded it 99 times out of a hundred in a youth match. I do think it is wrong that Fabregas, Costa or anyone with a reputation for exaggerating contact is likely be treated differently from Vardy there, but given his speed at the time and the position of Monreal's leg, it's easy to see why Martin Atkinson pointed to the spot. Apart from not noticing a more obvious 'dive' from Mahrez in the second half, I thought he handled the game very well.
Furthermore, over the last five or ten years has the pointed interest in simulation not become disproportionate and contributed to widening the grey areas in law? Like handball offences, it would put everyone more at ease, I feel, if referees were advised to react to a clear foul/instance of unsporting behaviour, as opposed to trying to root out suspect tendencies through affirmative action/interpretation. Although discipline has probably improved over time, the priorities for referees should be to reduce tolerance of cynical fouling (persistent infringement is an insufficiently punished offence, and in that respect Atkinson did well yesterday with the dismissal of Simpson) and of dangerous tackles (e.g. Drinkwater on Ramsey). Perhaps I am alone here, but in terms of establishing a sustainable future for the game (aside from the debate on ancillary technologies), simulation strikes me as a non-issue in comparison.