Sky News has been told of the extraordinary account of Lukasz who was working in the basement at Fishmongers’ Hall when Usman Khan launched his deadly attack.
However, the death toll could have been higher but for the actions of a number of bystanders.
Describing the shocking incident, Fishmongers’ Hall chief executive Toby Williamson hailed his colleague’s actions.
“You’re not going to see Lukasz. Firstly he’s too modest and secondly there’s no camera footage,” he said.
“He’s washing up glasses in the basement. He hears the screams. He’s first aid trained so he makes the conscious decision to go upstairs. It’s pretty obvious what’s happening.
“The terrorist is brandishing two knives with victims all around screaming and people cornered.
“He pulls off the wall this narwhal tusk and takes the fight on. In the next minute he’s on his own.
“He’s buying time for others to escape. In that time he makes a stab towards the terrorist and knows something is wrong as he hits him in the chest and it bounces off.
“He’s got a vest on of some sort. At that point there’s a vicious knife fight in which Lukasz takes five cuts all the way up his arm. He’s hurt badly but doesn’t flinch for a minute.
“He’s then joined by two or three others, and now overwhelmed by numbers the assailant goes down the stairs.”
After another fight in the building’s foyer, Khan, 28, breaks through the doors on to the steps outside.
Mr Williamson added: “Lukasz is right behind him. He is hurting badly and has lost the strength in his left arm but he was there until the end.”
According to reports, Lukasz is set to receive an official honour in his native Poland, recognising his “sacrifice and courage”.
London Bridge has reopened in both directions, although the northbound carriageway is reduced to one lane due to ongoing police investigations. There is a heavy police presence in the area this morning, with officers stationed on both pavements and across the central reservation.
And around London Bridge station there are several boards with messages of support written on them.
One says: “Together we stand. An attack on any one of us is an attack on us all.
“Haters are not welcome. We are London and we won’t fall.”
Two forensic tents and a trailer are still on the north side of the bridge, with a police cordon running the length of one side of the bridge.
A vigil is due to be held to pay tribute to the victims of the attack and to honour the emergency services and members of the public who responded to the incident.
Mayor Sadiq Khan will be among those at the remembrance service at Guildhall Yard, where Londoners will be able to lay flowers.
It comes as West Midlands Police said a 34-year-old man arrested in Stoke-on-Trent on suspicion of preparation of terrorist acts has been recalled to prison due to a suspected breach of his licence conditions.
Officers from the West Midlands Counter Terrorism Unit arrested the man after a search of his home address on Saturday and inquiries into the suspected offences are continuing.
The force has said there is no information to suggest that the arrested man was involved in the incident at London Bridge.