"If you want to get out at the top with people wanting more, the timing of my departure couldn't have been better," says former Freshfields Bruckhaus Deringer partner Mark Rawlinson of his move earlier this week to Morgan Stanley.

He is not exaggerating. During the past year or so, Rawlinson has worked on some of the biggest deals in the UK market, including AB InBev's mega-merger with SABMiller, BG Group's takeover by Royal Dutch Shell and the London Stock Exchange Group's proposed merger with Germany's Deutsche Boerse. Not a bad haul for a man who admits he has asked Freshfields for the last two years if the firm would like him to retire, preferring not to outstay his welcome.

"I said a few years ago that I wanted to retire on my terms – I don't want to go out like Wayne Rooney, on the subs' bench," he jokes.

There is no chance of that, based on his recent activity. However, the downside of his M&A reputation is that for years he has been losing his key clients to takeovers.

"That's when you have to reinvent yourself – when you've lost a lot of your client base through mergers," he says. "That's when you have to start again and build a new roster."

It's a mountain that gets easier to climb the more experienced you become, as he readily admits: "It's a lot harder as a young partner – getting P&O and EMI was a lot harder than getting BG. When you're younger you're just saying: 'I'm young and enthusiastic, give me a chance'. Once you've been a partner for 10-plus years, you have a track record, people know who you are – then it's a lot easier."

Rawlinson, currently preparing to pack up his office at the firm he has called home since 1982, is at pains to point out that it hasn't all been about the deals.

In a world where work/life balance is in short supply – he readily admits to pulling 80-hour weeks for months at the height of the AB InBev deal – Rawlinson is keen to stress that his family has been equally as important as his job. (Those he has mentored have heard the same line, with one saying Rawlinson's top tip for future wealth and happiness was to buy his wife flowers every week.)

"Someone once said to me that in life you can do one and a half things well, or one thing perfectly. I think that most of the time I've given Freshfields three quarters and my family three quarters," comments Rawlinson. "Not a perfect partner, and not a perfect husband or dad, but I've made a reasonable fist of both."

At times, however, balance has been in short supply, given Rawlinson's standing as one of Freshfields' star rainmakers – a partner who, alongside the likes of Steve Cook or Nigel Boardman at Slaughter and May, corporates seek out in a crisis.

He was summoned back from holiday to advise AB InBev and also picked up his role advising BP on the Macondo oil spill crisis while on holiday with his family. He was on a walking holiday in Ireland when he received the call from BP group general counsel Rupert Bondy's PA asking if he could get on a plane back to help the company after its share price crashed amid the crisis, and it found itself a takeover target. "I told him, rather uncoolly, that I would swim back," he recalls with a smile.

Occasions like these mean that by Rawlinson's measure, there have been times when the firm has had his full attention and his family have been short-changed, and vice versa, but he leaves with no regrets about either.

The City now is a million miles away from 1980 – there was no email, no word processing, no mobiles, and liquid lunches

So what advice does he offers younger lawyers, both from his own experiences and those of mentors such as former Freshfields partners Anthony Salz, Charles ap Simon and James Davis?

"You start off as a technocrat and develop the client skills later," he advocates. "In 1987, after the Guinness takeover of Distillers, I spent a whole year answering questions about takeovers. It meant I knew takeovers better than anyone else in the firm, so I was first choice for any takeover work. When I became partner in 1990, I became an expert on rights issues and because of that I got involved in the P&O rights issue and had the chance to cultivate them as a client.

"You start off majoring on the law but you don't get to be a trusted board adviser because of legal knowledge. It's about having confidence to be clear and concise, to simplify the issue and the solution rather than trying to prove how clever you are."

A good dose of luck doesn't hurt either – you may make your own to some degree, but not everyone will have the opportunity to work with the Red Knights (the group of City financiers who mounted a billion-pound bid for Manchester United in 2010).

"Moving from being a good lawyer to a brand in your own right involves luck to differentiate yourself," he concedes.

Being able to talk plainly to clients and understand their mindset is also a differentiator, according to Rawlinson. "I'm just normal – a good bloke to be stuck in an office with all night. Being seen as normal and easy to understand has helped. There's a big difference in styles between me and a David Cheyne or a Nigel Boardman."

Aiding his own career progression was the era in which he learned his craft. Quite simply, it is harder to gain the same level of client/board-level advisory skills with less exposure to boardrooms and meetings.

"It is all so different to when I joined," he says. "The City now is a million miles away from 1980 – there was no email, no word processing, no mobiles, and liquid lunches. There wasn't a Goldman or Morgan Stanley in London in the 1980s. Then you were in meetings all the time: you learn so much in meetings about people and their agendas. But if you stand still you go backwards, and this firm has evolved to stay on top."

There'll be more activity over the next few years, not less – Brexit isn't a market-killer for M&A

He is under no illusion as to the advantages the Freshfields brand has given him. "How did I achieve what I did? Partly the people and partly the platform – Freshfields is an amazing platform. It gives you the opportunity to be the best at what you do."

As Freshfields man and boy, he is, unsurprisingly, most going to miss "the people", yet he elected not to go for a firm-wide management role, to the surprise of some in the market. His explanation is simple: "With the senior partner role my wife asked: 'Do you want the title, or do you want the job?' Will Lawes and Ed Braham both wanted the job – I didn't."

Instead, he plans to use many of the same skills he's developed as a dealmaker in his new role as chair of Morgan Stanley's UK investment banking arm. First approached about the role last summer, when a quieter start to the year meant he'd been considering what to do next, he wasn't initially sure the job was for him.

Now, though, he has no regrets about the role, despite the ever-looming prospect of Brexit, which has already prompted his new employer to suggest it may move some of its staff elsewhere.

"It's a purely client-facing role, trying to get work in and then strategic advice. It's similar to what I've been doing here. Over the last 10 years only 10%-15% of my advice has been legal – the rest is strategy: how's it going to pan out? Clients don't ask what the law is; they expect me to know that. They ask: 'How do I do this?'

"I'm looking forward to it – it's a great job. There'll be more activity over the next few years, not less – Brexit isn't a market-killer for M&A."

budweiser-bud-light_424499-Feat-201610051810Rawlinson on his top three deals

"Ten months for the most complex deal ever is massively fast. Shell took 10 months and that didn't have any substantive competition issues. Everything about this was complicated, but the company was incredibly proactive, which made it faster. They announced the first sale at the same time as the deal. They are always looking at something – they're a deal machine."

"It was one of the cleverest deals I've ever been involved in – we thought through every step and scenario and planned what to do. It started life as a merger with Royal Caribbean with a poison pill JV, which had a deliberate flaw to allow Carnival to get involved."

"It's my club. I was born in Manchester, went to see them in the days of Best, Law and Charlton and it was the first time my dad (even as a Man City fan) thought I must be quite good at what I do. It partly led to the Red Knights, which in turn led to BP calling me in to do Macondo."