It’s a pub like any other. Traditional, wood panelled (old wood) with a real bar (brass?). There’s a perimeter shelf for empties (nice touch) and a place for coats (polite). Perched on high seats huddled around circular tables with cheap beer mats. The bar is awash with suits finishing work. It could be the bar of a provincial Wetherspoons in an old civic building turned public house.

But this is a bar like no other.

The beer garden looks over a sheer drop to the Thames and smoker’s corner is guarded by an armed police officer. A sign above the bar decrees that ‘Only members’ may purchase drinks.

Members as in Members of Parliament.

This is the most powerful working man’s club in the land. I stand, out-of-place, wondering how many decisions supposedly made in the Chambers along the corridor were actually made in here, the members bar? How many votes have been swayed under the influence of a hand-pulled beer rather than the glare of unhappy backbenchers or a fuming whip?

It’s from the Chambers that our host marches towards us having just pitched his argument in a debate about air ambulances. Greg Mulholland has an air of relaxed confidence about him as he introduces us to the collection of MPs and industry experts gathered today. And he buys us all a pint, which is fitting, because we’re all here to talk about beer.

Actually, I’m a gatecrasher, having assumed my pre-arranged pint with Greg would be down the road in the Red Lion or one of the pubs that scatter Whitehall.

Instead I’m directed by his office to the visitor entrance of the House of Parliament. And then I’m ushered through scanners and eased towards a large-lens camera and shuttled to the doors of the Palace of Westminster.

Gladstone stares down at me; Disraeli too. I’ve passed the steps where Spencer Perceval died, the only British Prime Minster to be assassinated.

And after dropping in on all-party parliamentary beer group session with Visit Britain and Roger Protz, I find myself in a MPs only lift shuttling down the creaking floors to grab a beer and chew the cud with the members and industry experts.

Amongst the rotund suits and red-faced seats of power are civil servants, guests of honour and representatives of associations, clubs, movements, charities, lobbyists, think tanks, quangos. Least that’s what they look like. In my jeans and brogues and tie-less Oxford shirt I like to think I look like a young entrepreneur or digital strategist or media advisor.

In truth I look like an awestruck school child staring high up at the lofty spires of the Palace of Westminster with naive wonder, thinking of the Empire that grew out from this spot and contracted back towards the banks of the hazy river below.

Three pints later the policy makers are chatting about their wives and their weekends, their husbands and their holidays, and again I’m wondering how many parliamentary decisions are made in the twilight sun as the powers that be overlook the Thames sipping beer and wine.

On a summer’s evening like this, I wonder if it’s any at all.