The Liberal Democrats have taken up cudgels on behalf of those signed up to the Telephone Preference Service, which is supposed to stop nuisance sales calls.
They claim that calls made by Tory and Labour canvassers to these numbers are unlawful and have made complaints on that basis to the Information Commissioner. The Labour view is that this is incorrect, as the calls aren't being made for marketing purposes, but to establish voting preference.
I can't help but suspect one or two ulterior motives here. Firstly, we know that Liberal Democrats tend to do well when turnout is low (by-elections and local elections are key examples), so have an interest in keeping voters at home. Secondly, the LibDems aren't as well-off (or as far in debt) as the other two parties, so aren't able to afford the call-centres working flat out to identify key voters.
Maybe I'm just being cynical here, but I just don't put trying to generate interest in the democratic process in the same category as flogging double-glazing.