Revellers planning to host a barbecue next week should consider one-way systems of travel around the grill and bringing their own condiments, an expert has said.

From Monday, groups of up to six people in England will be able to enjoy socially distanced meetings in parks and gardens, including hosting barbecues, Prime Minister Boris Johnson announced on Thursday.

Behavioural neuroscientist at the University of Reading's School of Psychology, Professor Patricia Riddell, said the Government guidelines around this are unclear, and recommended some measures those worried about spreading the virus could take to stay safe.

Prof Riddell said people should not feel obliged to meet larger groups just because it is legally allowed, but for those who do, their most important consideration is their guest list.

"The first thing I would be doing is thinking who do I want to include in my group - who has been taking the same level of risk that I have and won't put me and my family at risk?" she said.

"As harsh as it sounds, some people are on the front line and are exposed to the risk, and you need to be aware of the risk they might bring."

Prof Riddell recommended asking guests to bring their own cutlery, plates and condiments to reduce the risk of virus transmission through touching the same surfaces, and having only one person using the tongs.

She also endorsed serving food on plates from a distance rather than everyone approaching the grill, setting out seats in advance for people to sit two metres apart, and sitting alongside each other rather than face to face.

"You could have routes of travel so people go round one way to the barbecue," she said.

"I think you could make it quite good fun, almost like an obstacle course or game.

"Instead of forcing rigid and hard rules, make it imaginative, creative and fun.

"There's going to be greater pressure on us to do more, especially from our kids, and it's about how do you do it in a way that's fun but also takes into consideration that we are still at risk."

After announcing the new restrictions at a Downing Street press conference on Thursday, Prime Minister Boris Johnson said: "What you certainly can imagine is there could be meetings of families in a garden, you could even have a barbecue provided you did it in a socially distanced way, provided everyone washes their hands, provided everybody exercises common sense."

Professor Chris Whitty, chief medical officer for England, also told anyone planning such gatherings it was "absolutely critical" to maintain strong hygiene standards.