Next week, Nick Clegg will return to Westminster as an ordinary backbencher from a small, minority party. And, for a while at least, he may be content to spend (in that much abused phrase) more time with his family, and concentrate on his duties as a constituency MP. After all, Sheffield Hallam is one of only eight in the whole country to re-elect their Liberal Democrat MP. And as Clegg has spent the past five years as Deputy Prime Minister, you could argue that he now owes his constituents some undivided attention.

He may have in mind a return to Brussels in some capacity one day, but this would surely have to await a time when his departure would not deplete Lib Dem representation in the Commons. In the meantime, as a prominent pro-European, he could reasonably claim leadership of the “In” campaign in the coming EU referendum. But it is hard not to feel that, however well he re-adapts to the back bench, and whatever part he might play in the referendum campaign, Clegg has more to offer, and that – with a little imagination on David Cameron’s part – there could and should be another role for him. He has gifts that are rare in British politics, especially at present.

As the Lib Dem leader and Deputy PM, Clegg showed himself to be an attractive and highly competent performer in the two forums – Parliament and the media – where today’s politicians need to excel. He took on the risk of a regular live radio slot (on LBC), and managed, over more than two years taking calls from the public, almost never to make the wrong sort of headlines. In government, he was liked by his staff and civil servants, he was able to make decisions, and he remained calm and good-humoured under sometimes very unfair fire (tuition fees, and joining the Coalition at all). He was discreet and remained loyal until the election beckoned. In my book, at least, those are virtues.

One of Clegg’s greatest strengths, however, went largely unseen and was little remarked. Throughout his time in government he was an enormous asset to Cameron in international diplomacy, especially – but not exclusively – with Europe. Foreign policy was never Cameron’s forte, either as leader of the Opposition or during his first term as PM. “Abroad” was where Cameron made most of his misjudgements – all by himself.

Bidding for the leader’s job, he misguidedly promised to take Conservative MEPs out of the centre-right EPP bloc. Even more misguidedly, he honoured that promise once he became prime minister, which diminished his, and the UK’s, influence in the European Parliament. Cameron then thoroughly messed up one of his early EU summits, flouncing out at 5am after vetoing a joint plan to save the euro. Clegg, it was reported, spent the next few days almost continually on the phone, exploiting contacts from his Brussels days to mend badly broken fences.

Best General Election 2015 quotes Show all 10 1 /10 Best General Election 2015 quotes Best General Election 2015 quotes 1. "Am I tough enough? Hell, yes, I'm tough enough." Ed Miliband bats away suggestions he would be too weak on the international stage. It likely to go down as one of the quotes we remember this election by. Matthew Lewis/Getty Images Best General Election 2015 quotes 2. "If I'm getting lively about it, it's because I feel bloody lively about it." David Cameron attempts to prove how passionate he is about wanting a second term as Prime Minister after Tory donors criticised his lack of enthusiasm. AFP Best General Election 2015 quotes 3. "Oh it's crats? I thought it was Liberal Demo-cats" Reality TV star Joey Essex is taught a thing or two during his meeting with Nick Clegg. PA Best General Election 2015 quotes 4. "Brain fade" Green party leader Natalie Bennett gave what was described as the "worst political leader's interview ever" on LBC Radio as she fails to answer how the Greens would pay for its ambitious housing policies. LBC/YouTube Best General Election 2015 quotes 5. "We're a shining example of a country where multiple identities work. Where you can be Welsh and Hindu and British, Northern Irish and Jewish and British, where you can wear a kilt and a turban, where you can wear a hijab covered in poppies. Where you can support Man Utd, the Windies and Team GB all at the same time. Of course, I'd rather you supported West Ham" David Cameron experienced his own brain fade when he forgot which football team he supported. Getty Images Best General Election 2015 quotes 6. “This is a real career-defining … country-defining election that we face in less than a week’s time” The Prime Minister made another gaffe when he made it sound like the election was all about himself. BBC Best General Election 2015 quotes 7. “Ed Miliband stabbed his own brother in the back to become Labour leader. Now he is willing to stab the United Kingdom in the back to become prime minister.” Defence Secretary Michael Fallon launched a vicious personal attack on Ed Miliband. PA Best General Election 2015 quotes 8. "Ajockalypse Now." The colourful term used by Boris Johnson to describe a Labour government propped up by the SNP. JUSTIN TALLIS/AFP/Getty Images Best General Election 2015 quotes 9. “The SNP are openly racist. The anti-English hostility, and the kind of language that is used about and towards English people, is totally extraordinary.” Nigel Farage launches an attack on Nicola Sturgeon and her SNP party. AFP/Getty Images Best General Election 2015 quotes 10. "Terms are like Shredded Wheat. Two are wonderful, three might be too many." David Cameron rules out a third term as Prime Minister. Getty Images

As Opposition leader, Cameron misread the brief Georgia-Russia war. As PM, his enthusiasm for the Libya intervention was ill-judged, as was his approach to Syria – support for air strikes and a lost vote in Parliament. Nor does he travel well. The confidence he showed at home often seemed to desert him. He looked ill at ease even in the United States.

Nor did his foreign secretaries do much to offset that weakness. William Hague brought his inimitable character to British diplomacy, but it was of a very English sort. Philip Hammond, Cameron’s second, and now reappointed, Foreign Secretary, evinces precious little character at all. Perhaps that will change, but it is hard to see his tenure as much more than functional, to keep the show reliably on the road.

Nick Clegg, on the other hand, travels extremely well. It is not just because he is an accomplished polyglot – which sets him apart from many a UK official. It is also, and more significantly, because he is multicultural in the best sense: of cultural sensitivity. He can blend in at international gatherings and talk to others in a modern idiom and on equal terms. He comes across as trustworthy, affable and relaxed – a combination many official Britons find nigh-impossible to muster abroad.

Clegg also has direct experience of working, and succeeding, in Brussels. With the referendum in prospect, this is surely the arena where he should be deployed. Cameron badly needs to extract some changes from Brussels that will allow him to argue for staying “in”. Actually securing them, however, is another matter, and at least half the battle will be to know what is feasible and how to prepare the ground.

This is where Clegg could be indispensable. He will know what can and cannot be asked for. He will know how to make the early approaches, where there might be room for movement and how not to put people’s backs up. He cannot be the UK’s lead negotiator; George Osborne is already in place. Nor should he be. A formal role for Clegg would only exacerbate Cameron’s difficulties with his party’s Eurosceptic wing.

But as an adviser, a go-between, a smoother of the way, and a sounding board (for both sides), Clegg would be invaluable in preventing mistakes before they happened. He knows how Europe works, he knows how Cameron and Osborne work, and he knows how to be discreet. Used to organising his time, he could be a special envoy without unduly detracting from his work as an MP.