So, my understanding of the single market is this. At the moment, every country has it's own regulations governing all sorts of things about the products that can be sold in their country. For example, some countries might say that a product has to fulfil a particular environmental or safety standard. The laws, standards and regulatiions are different for each country. If the UK want to sell products in these countries, then the products they make will have to meet the varying standards of the different countries. This effectively means having to make things slightly differently for each country they are going to sell to. However, everyone in the single market has agreed a common standard and regulations about the products sold. Therefore, manufacturers don't have to spend time and effort adapting their products to sell to individual countries. If we leave the single market, manufacturers will therefore have many more complications in terms of making and selling their products. Manufacturing costs will rise, profits will fall to accommodate this, products will be harder to sell, unemployment will rise and UK companies will be less appealing to investors. Oh, an the financial sector will just leave London and move to France / Germany because it's totally dependent on the single market.
Have I got this right? If so, given that Gove is determined to take us out of the single market, we're all buggered to buggery.