There is. I've even told you about it before. Please stop repeating this lie.
This is PC Alan Palfrey (127EK):
Here he is again in riot gear:
Here, at 7:20pm he's just witnessed Simon Harwood's attack on Ian Tomlinson:
And here he is at 7:33pm outside 77 Cornhill, where Ian Tomlinson had collapsed minutes earlier:
There's no way he could pass along Cornhill without having seen Tomlinson on the ground or being carried away.
The other officer in the centre of the second photo is Steven Discombe (2558CO), who Palfrey accompanied throughout April 1st. Discombe is - in his own words - "a Public Order Field Intelligence Officer; this role gives me specific responsibility for several protest areas, one of which is Anti Capitalism. I have responsibility for the monitoring of Anti Capitalist demonstrations within the Metropolitan Police District."
To suggest that PC Discombe was either unobservant of the collapsed person at the demonstration, or unable to communicate what he had seen to more senior officers is nonsense. Again, it is impossible that he could have passed Tomlinson on Cornhill without seeing him. Both officers made statements to IPCC investigators about Tomlinson.