Love-struck Norwich North MP Chloe Smith said she was 'incredibly proud' to announce her engagement to a former soldier who she proposed to after a four-month romance.

The politician declared it was 'love at first sight' when she met her husband-to-be Sandy McFadzean at a London charity event organised by a mutual friend in the summer.

Although the couple had discussed marriage before, Miss Smith surprised her new fiance by unexpectedly popping the question last weekend.

But he didn't say yes straight away – preferring instead to take the opportunity to quickly seek out the perfect platinum and diamond ring, and to propose in traditional style himself later the same day.

Mr McFadzean, 34, was born in Scotland and grew up in north Wales before serving on a short service commission with the Parachute Regiment. He is now a financial consultant with London-based firm Catalyst Development.

Miss Smith recalled that on the evening she met her sporty future husband, he had just completed a triathlon.

'By the time we met that evening, Sandy had swum to shore from the Isle of Wight, cycled 100 miles through the New Forest and run a half marathon into London, and still made it to the charity ball,' she said. 'He is welcome to repeat that with a box of Milk Tray any time he likes.

'I just loved the way Sandy talked. I was instantly attracted to his really relaxed manner and we just hit it off straight away. We share a great interest in the way the world works and what makes people tick.'

The couple also discovered they had both worked for the same financial consultancy, Deloitte – although at different times.

Mr McFadzean said: 'I work in financial services and Chloe was in the Treasury at the time. When I told her I work with banks and financial regulation she said: 'We can't talk about that', so that was a Chinese wall right there.

'But we soon found other things to talk about. It was very relaxed and we clicked very easily. We share a sense of humour, which is a very important thing.

'We realised really quickly that we wanted to be together, and we talked early on about the fact that we had found each other and hoped to spend a lot of time together. By some sort of unspoken plan, we started introducing ourselves to each other's lives. There was a clear sense of direction... and then Chloe decided to short-circuit it!'

That moment came in the early hours of the morning in a rare gap between political engagements.

Mr McFadzean said: 'One of the features of our relationship is that we have quite clear views on equality and we are a very equal couple. When we talked about marriage, I think I made some sort of comment along the lines of: 'Why does the pressure have to be on me'. The next thing I know she has asked the question.

Miss Smith said: 'The silly man should have known better than to lay such a challenge. He didn't say yes straight away, he was just wide-eyed and beaming.'

Mr McFadzean said although he had done some military training at Thetford he had never been to Norwich before falling in love with one of the city's MPs.

'My parents live in Scotland near Perth, which is a very similar city to Norwich,' he said. 'It is a very beautiful city and I have really enjoyed getting to know it better. I am very proud of Chloe and the fact she works so incredibly hard for her constituents, and for the city generally. It is one of the things that impresses me most about her. I am not part of her political team, but I will always support her as any partner, fiance or husband would.'

Miss Smith said: 'I have been very careful to make sure Sandy sees every side of what I do, because it is a funny old job. He is not just another pair of hands but he has come out with me and seen the kind of work I do, meeting the constituents and knocking on doors in the rain.

'It has been a real privilege for me to be able to invite Sandy to take part in events in Norwich. With his background, I was particularly pleased to ask him to join me for the Remembrance Day service last month. I think that was the first time we attended an event together in public.'

The engagement was confirmed just a week after Miss Smith met Mr McFadzean's parents and three sisters in Scotland, who were 'delighted' with his choice of partner.

When the roles were reversed on a trip to see Miss Smith's parents in Stoke Ferry in West Norfolk, Mr McFadzean got equally good reviews from the prospective in-laws.

'I had been full of it from the beginning,' said Miss Smith. 'I think it was just shining out of us that we should be together. My parents absolutely loved him, and so did my grand-parents. My brother is in New York, so they have met via Skype. He is also a management consultant. The funny thing is, you should see how organised our wedding spreadsheet is!'

No date has yet been set, but the couple are planning a family wedding in Norfolk next year.

'We are both very private people,' said Miss Smith. 'I do a public job, but this is the first time I have told people about my private life. I am just incredibly proud to be with Sandy. He makes me deeply happy and we are looking forward to a happy future together.'