Attendees face restrictions on face masks, social distancing and travel arrangements
While the prime minister faced criticism on social media, other images showed him wearing a mask while the veteran broacaster, who was sat next to him, had his off.
But the virus has not gone away, with the UK recording between 30,000 and 40,000 daily cases over the past month.
Nicola Sturgeon, the Scottish first minister, said the Glasgow climate summit – which brings delegates from around the world to meet indoors in large numbers – “inevitably poses a risk of increased Covid transmission”.
But the government was doing all it can to mitigate risks, she added.
The summit has a host of measures in place in a bid to prevent any potential outbreaks, including rules over face coverings and social distancing.
Visitors to Cop26 must do a pre-departure Covid test and have been strongly advised to get vaccinated against the virus.
Specific arrangements have been made to facilitate travel to the summit, with double-jabbed registered attendees facing a reduced quarantine period of five days if they have visited a red-list country in the 10 days prior to their arrival in the UK.
Unvaccinated guests must quarantine for the standard 10 days.
In the Blue Zone, which is only for official attendees, everyone must wear a face covering except for in specific circumstances, including when in meeting spaces or conducting negotiations, or when medical reasons apply.
Event speakers can remove masks when delivering a speech, but members of the audience should wear masks when sitting in theatre-style seatings.
Blue Zone guests must also do daily tests for Covid, showing negative results at entry points, and mst stay at least one metre away from one another.
All delegates will receive hygiene kits, which include a reusable mask, hand sanitiser and antibacterial wipes.
In the Green Zone, which is open to the public, proof of vaccination is needed to enter and guests are told to wear face masks in all indoor public spaces in line with Scottish law.
Those officially involved in the summit have been asked to focus their activities in the Blue Zone and urged to not frequently travel between zones as a safety measure.
The Cop26 comes just months after the G7 summit in Cornwall over summer, which saw St Ives deal with a surge in coronavirus cases thought to be linked to the event.