Given that the Japanese car industry invested in the UK to gain an entry to Europe, I would expect that our departure would see a significant change in investment in this country. Equally, I would expect to see a detriment to exports.

Andrew Bolton, Staffordshire

Trade with the EU is so important to both sides that they’d ensure it was unaffected. We’d still contribute to, and benefit from, sensible, Europe-wide standards. We’d save a bit of money and lose a bit of red tape. The sector would cope.

Bill Ball, Lincoln

I do not believe any referendum should be held on this issue. We are part of Europe – we should not even think about leaving the EU. The politicians should not be bowing to pressure for such a referendum.

Ian Marks, Rugby, Warwickshire

‘Cast-iron’ is an excellent image, because I expect the ‘commitment’ will be broken before the end of 2017. If we did leave, then the engineering sector would prosper. The number of piffling regulations would reduce, although our own civil servants would do their utmost to take the place of EU law-makers. 

William Richardson, Haddenham, Buckinghamshire

I thought Cameron had no idea what engineering was, but I was wrong – cast iron is strong but easily broken.

David Hanson, Milford on Sea, Hampshire

We would continue to trade just as effectively with Europe – and perhaps get better at trading with the US, China, India and Russia. We would revert, however, to laws developed more through precedent and common sense than by extended, inefficient, undemocratic, multinational committees. 

David Mortimer, Lancashire

Withdrawal from the EU would increase bureaucracy for trade between the UK and mainland Europe, probably increase taxes and probably disadvantage the UK. Any standards changes in Europe would have to be separately shadowed in the UK, and would further disadvantage mutual free trade.

Brian Burgess, Selby, North Yorkshire

We might win in some respects, but the overall result would be a disaster. Even having the vote is sending the wrong message and may have a detrimental effect.

Crawford Murray, Sussex

Disastrous, catastrophic, apocalyptic – or possibly challenging, refreshing, exciting. We can take on challenges but we need the best opportunities, and they are provided within the EU.

Richard Lindop, Duffield, Derbyshire

Cast iron’s properties are improved by alloys. For ‘cast iron’ read ‘the UK’; for ‘alloys’ read ‘the countries of Europe’. Therefore, leaving Europe would weaken the UK, leaving a brittle structure.

Harish Narotham, Crewe, Cheshire

High-tech engineering requires collaboration. A lot of engineering companies do this with partners across the EU. To withdraw would be bad. Many engineering employers in the UK work closely with EU-based partners, to develop and/or manufacture products.

JJ Dring, London

Geography and market forces would tend to maintain the status quo, and we might even benefit from being a bridge between the EU and the rest of the world. It is tempting to think that we would benefit by being released from EU directives, but our own civil service has shown that it is equally adept with red tape.

Gib FitzGibbon, Ayrshire

I believe that it would be a negative effect. Even though Europe has opened the UK to mass migration, it has also opened it to more business, which means more jobs. 

Amarjit Matharu, London

Provided that we maintain a similar relationship with the EU to that 

with Norway or Switzerland, then there should be no real issues. Passports are already required for travel in and out of the UK, and if we stay a part of the free trade agreement, there shouldn’t be any impact on business.

Stuart Cadman, Gaydon, Warwickshire

Preventing free movement of engineers, and limiting the available talent pool both within and outwith the UK, could leave us isolated and less globally competitive. EU regulations do, however, need simplification to promote growth, particularly for smaller companies.

Allan Wilson, Aberdeenshire

My heart says ‘out’; my head says ‘in’. We plough billions into an inefficient conglomerate that appears to achieve little. But I would not gamble on the employment and export implications if we came out.

Gary Lock, Dorking, Surrey

It would be a disaster. All trade with Europe would still need to meet EU standards and regulations, but we would no longer have any control over them, and would have cut off business opportunities and soured trading relationships.

Simon Dodd, Leicester

At first, we would hardly notice. But gradually our influence would diminish and the EU would head down paths we might not like but would have to accept. We would become like an elderly family dog, left in the corner to growl to itself. 

David Odling, Altrincham, Greater Manchester

We might have to reinstate some British industry. What a pity.

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