Denise Martin was the first to spot the suspected lion yesterday evening from the windows of her caravan near Clacton. She said it was tan coloured with a white chest.
Mrs Martin, from Canvey Island, was spending the Bank Holiday weekend at the site with her husband, and brother.
"I was looking out of the window and we saw smoke - it looked like there had been a bit of a bonfire. When you are in a caravan you panic about smoke,"
"When the smoke cleared I could see this shape in the field, so I got the binoculars out. We had a look and it looked like a lion.
"I said to my husband 'What do you make of that?' He said 'That's a lion.' We walked out of the caravan nearer to the field to get a better look.
"Five or 10 minutes later we got my brother and my sister-in-law to have a look. They came and looked at it and said 'It looks like a lion.' My husband phoned the police."