From the report:
Air Accidents Investigation: Boeing 757-204, G-BYAT
The SCCM then returned to the forward cabin and contacted all the crew using the Alert Call on the cabin interphone. They confirmed that there was a pungent burning smell throughout the cabin; there was no smoke, but the smell was strongest in the rear of the aircraft. However, the flight crew did not respond to this call.
The SCCM returned to the flight deck to update the commander, and while the flight crew acknowledged her presence, she did not convey her concerns on the need to evacuate the passengers as the flight crew were busy dealing with the incident. She considered that she needed to disembark the passengers as quickly as possible and so, as there were no steps at the rear of the aircraft, when she returned to the cabin she announced, in a calm manner, over the passenger address system: “Please evacuate the aircraft as quickly as possible. Leave all hand baggage behind.” The cabin crew at the rear doors re-armed their doors and deployed the slides. A total of 43 passengers used the slides, with four of them receiving minor injuries.
(Emphasis mine.)
Not a very clear command - perhaps she intended the passengers to simply hasten disembarking via the (already open and in use) forward door and aerobridge?