On one level they are hundreds of joyful, spirit-lifting paintings of poppies. But for the artist Brian Clarke they are also a kind of diary of the pandemic – the highs, the lows, the loss and the hope.

Clarke is best known for his work with architectural stained glass, but he also paints, and over the last year, through the lockdowns, he has been obsessively painting poppies.

More than 500 of the watercolour paintings have gone on display at the Berkeley Square galleries of the London auction house Phillips.

Seen together, they represent a kind of pandemic journal. “It wasn’t a conscious thing of wanting to illustrate what’s going on,” said Clarke. “It just happens because you’re just there, you’re wearing your mask, you’re isolating, you’re not seeing the people you want to see.”

Brian Clarke has dedicated his collection of poppy watercolours to his late friend Linda McCartney.

Some works have lots of poppies clustered together, perhaps expressing a hope that if we are together, we are stronger. Other poppies droop, sag and decay. Others stand proudly by themselves.

At least four works feature the disposable masks that were used in the early days of the pandemic. “I thought I’d done 20 or 30 of them to be honest.”

Clarke said he had been painting the poppies night and day right the way through the pandemic. “When you’re working and it’s going well, you don’t want to get out of the water you’re swimming in. I’d wake up and paint them and then I’d go to bed irritated that sleep was interrupting what I needed to be doing. That carried on for a year, on and off.”

At one point, everything about the pandemic got on top of him and he started drawing skulls and abstract designs for stained glass, but he soon went back. “I couldn’t keep away from the poppies.”

It is a display “quietly dedicated” to his friend the late Linda McCartney. Clarke said McCartney would buy poppy seeds, the kind you put on bread, “and she would sling them out of the car window. You’d come back and see a line of poppies by the road. I can’t look at a poppy without thinking of Linda.”

Clarke said poppies also reminded him of the stained glass he is better known for working with. “The petals are so thin that the light shines right through them so naturally.

“It just takes the smallest little blow on a poppy and the petals dance all over the place.”