Is it legal to have a disposable BBQ in a public park?

We are planning a get together tomorrow, nothing to do with the wedding, it's to mark a year passing since a mate died. A few of the people are adamant is should be a BBQ, I can see it turning into a farce and us getting chucked out. Also, I tend to agree that safety wise it's not the best plan but it's not up to me to make the rules. Is it legal?