I hope somebody can help with this. I expect it is not that complicated but having never done it I'm just not sure.
We're getting close to the end of our fixed-rate term of our mortgage and are thinking about remortgaging to get a better deal. But, we bought close to the top of the market and have only paid off about 14% of the original value (including our 10% deposit).
I think that if we revalued the house for a re-mortgage they would value it for quite a bit less than we paid and we probably wouldn't have the 10% deposit needed to get a good deal on the new mortgage.
I'm not so worried about being turned down for the re-mortgage, but I AM worried that it would somehow affect the mortgage we've got currently. Could they do something nasty to us if we had next to no equity? 
Thanks for reading!