[QUOTE=acsenray]
I gather that even if the balance of power is not at stake in parliament, a bye-election still garners interest as a kind of barometer of the public approval of the government …
[/QUOTE]
Re. barometer of public opinion, well not always, but quite often, albeit that often the media are looking for one where there is none really. However, there have been a few recently:
Haltemprice and Howden did not matter much, it being a bit unusual, to say the least.
The Crewe and Nantwich by-election appeared to come of something of a shock (not a surprise, though, I shouldn’t think) to the ruling party.
The most recent by-election in Glasgow East on 24th July will be something of a barometer, because it was previously considered a VERY safe seat for one party, and this was particularly because it was thought that Gordon Brown could count on certain constituencies in Scotland. Of course, considerations regarding the financial probity of the retiring Member of Parliament were some cause for this change of vote, but for some voters, this would have been a vote about the current government. And voters might just have been a tiny wee bit upset about details such as food and electricity and fuel in general becoming a LOT more expensive, and so on. That sort of little detail. 
Sadly the Monster Raving Loony Party did not stand in this most recent by-election. A bit sad, because who can not love a party that had a cat as a joint chairman. (Unfortunately, the beloved leader, Cat Mandu, met a road accident in 2002 and thereafter failed to do the nine lives trick. Sad.) Likewise, poor old David Screaming Lord Sutch Screaming Lord Sutch - Wikipedia had died previously.
I think perhaps the dear old Monster Raving Loony Party just might not choose to afford the deposit these days. A bit sad, but there are quite enough nutters around for the moment, and interesting enough they are.