DON'T PANIC!!! The DVLA will get in touch with the owner shortly.
We have a van that is only used for sporting purposes for DS. Due to DS having had an operation and not able to partake in his sport for some considerable time, we innocently didn't renew van's insurance (although tax disc was still valid). It is parked on our driveway, on a private road, and wasn't being used.
We got a rather threatening letter from the DVLA telling us we had to "SORN" it (Statutory Off-Road Notice", I think it stands for) because the insurance had lapsed. I didn't think the insurance mattered too much as we weren't using the van, and it still had the tax disc, even though it isn't parked on a public road.
Do you know who the owner is, Gruntled, ie, is he/she a neighbour, or do you genuinely think it is an abandoned vehicle? If the latter, then report it, if the former, then it does sound a bit Victor Meldrew-ish. 