You clearly have a good knowledge of this subject, which I respect.
Its what I do for a living so I have some strong opinions on the subject

In Scotland they cab store power in pumped hydro electric stations
Very true, some in Wales as well. Energy stored in these facilities can be converted very quickly to electricity if required. Still require electricity to pump the water back up though

Electric cars are certainly one way forward and this is the first that looks, err, well, a bit sexy for want of another adjective. (Most of the others look like a Mr Man prop!). The only problem is the battery - expensive and environmentally costly to make - and the same to dispose of at the end of its life. Still, with the current pace of technology, I'm sure super-efficient and cleaner batteries will appear in the next half a dozen years, or so.
My fundamental issue with electric vehicles, they still need charging which still requires electricity generation which still involves the use of nuclear of fossil fuels.
However, I think you may be missing my point a bit. As I understand it, while coal station technology has improved greatly, they nevertheless take a long time to get up and running and are thus usually used to provide base loads.
The newest station is Drax (coal fired) and that was built in the late eighties (twenty years ago). Most are more like fourth or fifty years old. Generators have strived to improve thermal efficiencies of their stations and some work has been carried out in this area (nothing dramatic however). The other area of focus for coal stations is in emissions and there have been dramatic improvements in this area.
Coal fired units can be brought on load within an hour which is actually very fast. Nuclear units take longer (3 days). Most coal stations provide frequency response as well as base loading. In fact, the majority of the frequency sensitive units connected to the grid are coal fired. Running regimes differ between generators, some have long term agreements in place and may well base load. Others take advantage in the fluctuations in the wholesale electricity price and largely two shift their units. The message is that coal is flexible.
Nevertheless, whilst output may be more controllable, the energy input, certainly with regard to coal, is pretty much fixed to the target base load requirement. Thus, the amount of fossil fuel burned will remain pretty much stable 24 hours a day. By extrapolation, switching off a row of street lights will not, if the supply is from a purely base load source, have any effect on the power station emissions, which was the point I was making.
Less demand means less generation, fossil, nuclear or renewable. Nuclear is used to base load and is not frequency sensitive, so in reality it would result in a reduction in generation from the coal/gas fleet.
I understand that these days less energy is wasted because of the international grid, but I'd bet there may be times when overall base load supply exceeds consumption throughout Europe and it would be nigh on impossible to sell the excess. Indeed, while looking at Economy 7 (which is still be marketed, I notice) and storage heaters, I found this quote: "However, if a country's existing power distribution is such that base load supply exceeds demand during the off-peak period, then the storage heaters there are simply making use of energy that would otherwise be wasted."
In terms of the UK, we manage the frequency of our grid, we act literally as an 'Island' and we are not influenced by the European grid.
Interesting article can be found at
http://www.parliament.uk/post/pn163.pdf (its a little old but still relevant)
The majority of the European generation is in fact Nuclear. Their grid is considerably larger than ours and control of their distribution is across countries and is therefore more complex.
As for Economy 7, market forces apply. Less demand during the night time period results in a drop in wholesale electricity prices which is where the Economy 7 bit comes in. Its for this very reason that the Nuclear generators really suffered when the government introduced a different way of trading electricity some years back. The drop in wholesale prices was so dramatic that through night times and weekends, it cost the Nuclear generators more to generate it than they could sell it for, and because they are in-flexible they had to ride it out. Its why the government had to step in respect to the Nuclear generators.
Interesting thread, though!
It is an interesting topic and the challenges facing this country within the next 10 to 15 years with respect to our electricity supply are not insignificant. In my view, Nuclear and clean coal technologies are the only answer.