Detectives in the East Area Command Unit are investigating an assault that has left the victim in a critical condition.
Police were called at 19:33hrs on Tuesday, 8 May, following reports of a man having been assaulted at The Aldeman Public House on Chippenham Road in Romford.
The victim, a 51 year-old man from Romford, is believed to have been injured after an argument with another man.
The victim was taken to an east London hospital by London Ambulance Service where he remains in a critical condition.
His next of kin have been informed.
A 59-year-old man has been arrested on suspicion of grievous bodily harm and is in custody at an east London police station.
Any witnesses or anyone with any information is asked to call police on 101 or contact via Twitter @MetCC quoting reference 7658/08May.
To give information anonymously contact Crimestoppers on 0800 555 111 or online at crimestoppers-uk.org.