The restaurant and pub will call last drinks this week, after 16 years of trading from Kingston's Green Square.

Owner Ian Meldrum says rising liquor licensing fees, a decline of business activity in Kingston and an increasingly difficult regulatory environment have forced him reluctantly to shut up shop.

But he will certainly not leave empty handed, having acquired his fair share of potentially explosive secrets hosting at the regular haunt for senior politicians, backbenchers, staffers, journalists and lobbyists.

''I could tell you some stories that are unbelievable about their behaviour,'' Mr Meldrum said. ''You would worry about how this country is being run.''

Mr Meldrum even alludes, rather cryptically, to a collection of videos he holds of ''political figures behaving badly''.

But his former patrons needn't fear. Mr Meldrum believes in a code of confidentiality between those behind the bar and their paying customers.

''The one thing that is important to remember is that a lot of them are very decent, hard working and honest people,'' he said.

''Sometimes they confide in you with things they probably shouldn't, but out of respect I would never disclose any of that information.

''It doesn't do anyone any good.''

Mr Meldrum said the venue was still profitable, but says a host of new regulations hurt his bottom line.

The ACT government's liquor licensing scheme, which increased fees for the Holy Grail from $2000 to $16,000 a year, proved painful.

Mr Meldrum said the high vacancy rate in Kingston, huge costs for outdoor space and smoking bans had also hit hard.

''It's a reluctant move because the cost of doing business has just escalated so much in the past few years and profitability has declined to a point where it's not worth it for the hours you put in,'' he said.

It goes out with a bang on Friday night, with the party starting at 5pm.