Parking space is also at a premium as aircraft remain on stand awaiting deicing. Unfortuately, keen as they are, LHR has only a few experienced deicing teams. Many are volunteers drafted in for the winter.
Not sure about LHR, but where I work (that regional place up norf) the de-icing staff for the two companies who provide de-icing are either baggage handlers or cleaners, who are trained to de-ice in the winter months. There isn't any specific de-icing staff