Ah, the trappings of power.
As I sit down for lunch with Caroline Lucas in the vast, sunlit atrium of Westminster's Portcullis House, she kindly offers to buy me a sandwich.
Hardly a great moment in Parliamentary history you might think, but six months ago she would not have been able to do this.
The Portcullis House snack bar is for MPs and their staff only, you see - just one of the many perks, small and large, accorded to "honourable members".
The fast-talking, business-like Ms Lucas does not seem like the type to be seduced by the privileges of office, however.
As Britain's first ever Green Party MP, she says she is keenly aware of the responsibility resting on her shoulders.
The party she leads has battled for so long to gain representation at Westminster, that it falls to her to make the most of every minute and to ensure, in her words, "there is a green voice on all of the things that happen here".
To that end, she has dedicated herself to committee work, on the environmental audit committee and as chairman of the all-party group on fuel poverty and energy efficiency.
She has also thrown herself into her constituency duties in Brighton Pavilion, which at the moment seem to revolve around various housing woes. She is working insane hours, as a result, but is quick to praise her support staff.
But something is troubling the 49-year-old mother-of-two about her new place of work.
Like many new MPs before her, she has been first surprised, and then angered, by its strange hours and even stranger working practices.
As a veteran of more than 10 years in the European Parliament, where voting is done electronically on a giant scoreboard and is over in a matter of minutes, and speeches are normally limited to three minutes, the many traditions and quirks of life at Westminster - such as the "bobbing up and down" to catch the eye of the speaker - can take a bit of getting used to.
They can also take up valuable time.
"I have been deeply shocked by the lack of efficiency here at Westminster," says Ms Lucas.
"I never thought I would look back on Brussels and say 'that was an efficient system'. But, actually, in comparison with here, in many ways it simply was.
"The fact that half a dozen votes in Brussels would take you a couple of minutes maximum, either by raising your hand or voting electronically. Half a dozen votes here at Westminster can take you an hour and half. That is just not a good use of anybody's time. It's absolutely ridiculous.
"The way in which people can speak forever. We go on until beyond midnight, because there is no limit to people's speaking time and some people, unfortunately, like the sound of their voices a lot and it holds the rest of us hostage.
"We have got to bring this place into the 21st Century. We have got to make it a much more user-friendly, efficient, effective Parliament and it just isn't at the moment."
So, in addition to making her voice heard on green issues, she has decided to start a campaign to introduce electronic voting to the Mother of Parliaments.
There must be some way of speeding up the voting process, she reasons, perhaps with hand-held voting devices, with iris scans or thumb-print technology to ensure that MPs do not get their researchers to vote for them "and go down the pub".
"You could also make sure it was only operable within a certain distance of the chamber so, again, you are not having people in a restaurant on the other side of London voting, they are actually here on the premises," she adds.
She is drawing up a report on electronic voting and other reforms that she plans to hand to the party leaders, including her former European Parliament colleague Nick Clegg.
"I am not alone in feeling this, I am absolutely sure of that," she says.
"When I talk, particularly to the other women at, like, 11 o'clock at night and we are still waiting for some vote to come up and some person to stop talking, there is a strong sense that this isn't the way to do things.
"I think it's because we have got such a new intake of MPs, lots of them coming from other professional backgrounds. If they were doing this in any other realm of professional life, people would think they are absolutely mad."
So it is mainly the male MPs who like to hear the sound of their own voices?
"Empirically speaking, I have to say that it does look that way," she confesses somewhat sheepishly.
"I think it's just what people get used to, in a sense, isn't it? But I do think that having a more limited speaking time would concentrate the mind quite well."
It would be wrong to suggest that Ms Lucas is not enjoying her new career as an MP. She clearly is.
But she takes a pragmatic view of the place and freely admits that she had more power when she was an MEP.
"What you get in Brussels is much more influence over policy, you are a real co-legislator, and that's a fantastic opportunity.
"But the truth is, as far as the Green Party is concerned, we could double, treble or even quadruple our number of MEPs in Brussels and, sadly, the British media - and thus the British public - wouldn't know about it. Because, unfortunately, our media tends to be pretty uninterested about what happens in Brussels, in spite of the fact that increasingly large amounts of our policy is formed there."
"So the judgement I made, that the party made, was in order to have influence over the political debate, rather than policy narrowly defined, having someone, and hopefully more people soon, at Westminster is absolutely critical."
She also knows that to achieve anything she must form alliances with other MPs, regardless of their political persuasion.
"You don't get anything done by sitting in splendid isolation," she explains.
So far she has joined forces with everyone from Jeremy Corbyn, on the left of the Labour Party, on issues such as Trident, to Douglas Carswell on the right of the Conservative Party, on electoral reform.
She also insists that she will not be sidetracked by efforts to reform the institution of Parliament itself, which she says are just a small part of what she is trying to achieve.
She is also well aware of what she is up against from the traditionalists at Westminster, who are sure to fight any change to their time-honoured working and voting methods all the way.
Halting climate change is likely to be a doddle by comparison, she jokes, before heading back to her office in one of the far flung outposts of the Parliamentary estate, to get on with her work.