Alcohol is an important factor at a wedding. It is a celebratory occasion, so guests will expect to have a drink or two. Alcoholic drinks are also a very important budgetary consideration, and plenty of provision should be allowed for wine and champagne.
Marquee weddings are more economic because the bride and groom can choose and buy their own alcohol from a wine merchant or even on a booze-cruise.
The drinks bill at receptions in hired venues can quickly escalate when premium hotel prices or corkage are added on.