Holyrood's new bar – soberly titled the Queensberry House Lounge – is due to open after a £125,000 fit-out.
But it will not serve alcoholic drinks until 4pm, an hour after the Parliament's existing watering hole calls time.
Yesterday the move was described as a great pity by Independent MSP Margo Macdonald, a regular in the old bar.
Mrs Macdonald said: "The bar is not there for people to get roaring drunk but it is vital for informal talks between MSPs and between parliamentarians and the press.
"I think it's a great pity if the service is restricted."
She added: "I do constituency work there and I read the papers.
"It was the only place where you could get a comfortable seat in the afternoon, so I got into the habit of going. You met a much nicer class of person there. I
understand the hour's closure is to allow the staff a break but I'm afraid that's bad management. The service should continue all the way through, as it does now."
The new arrangements are part of a shake-up designed to end the £50,000 per year subsidy to the loss-making members' restaurant, where the existing bar is located.
From today the facility will close mid-afternoon and be used in the evenings for income-generating receptions and corporate events.
In its place a less formal bar has been created in former office space off the parliament's central garden lobby area. As well as drinks it will serve up-market pub food rather than the fine dining dishes enjoyed in the restaurant.
Mrs Macdonald, one of only a small handful of MSPs to have been given a sneak preview of the new bar, said the facilities were tasteful.
The veteran MSP's committed support for the old bar – dubbed the "White Heather Club" – prompted speculation the new bar might be named "Margo's" in her honour. She hopes it will become known as the "Heuchter Teuchter Hideaway".
MSPs and others with security clearance to work at Holyrood will be able to get a drink there until 10pm, with bar meals being served until 8.30pm.
The Scottish Parliament Corporate Body (SPBC) spent £75,000 fitting out the bar over the summer, with catering contractor Sodexo contributing an additional £50,000 to the cost.
A Parliament spokesman said: "The SPCB was clear that the subsidy of £50,000 for the evening service in the members' restaurant and bar was not acceptable and could not be sustained.
"Relocating the evening service is part of the SPCB's wider strategy to eliminate, over time, any subsidy for evening catering."
For MSPs for whom the "dry hour" proves too inconvenient, the nearest pub, Kilderkin, lies less than 100 yards from the Parliament's Queensberry House entrance.
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