With a low annual mileage insurance company algorithms may categorise you as an occasional inexpert driver, more likely to do short journeys at infrequent intervals, and nervous/unfamiliar with normal road conditions.

Think 85 year old, nervously once a week trip to the supermarket and old folks tea party..

Drivers who habitually do 8-12000 miles pa are more likely to be regarded as experienced, road savvy and alert.

Annual mileage doesn't have a huge effect on premiums.

It did with me when I was doing nearly 20k miles / year primarily because of a long commute - fortunately no longer, now back to a sensible 6k / year

Annual mileage doesn't have a huge effect on premiums.

Driver profile, employment status, address and car type are far bigger factors in determining premium.

I'd also avoid 'specialist' low mileage companies. Go for a general company and increase the mileage to 5,000.

I found when getting quotes that for all the normal insurers (i.e. not 'specialists' [I never realised they existed] for low mileage drivers) that premiums don't go down (at least not for me) for estimated mileages under 5000pa.

You are also correct about when increasing mileages it makes not a lot of difference until you reach around the 15k mark, as long as the work circumstances don't include a high risk job (e.g. sportsperson, journo, etc) or you 'travel for business', e.g. as a salesperson. Ordinary work travelling is fine - it only ever added on about £10 - £15 a year onto my premiums when I needed it, commuting (over SD&P only) £5 at most.

I agree that often 'specialists' are to be avoided unless you are forced into using them (for people with high risk or find it difficult getting insurance due to a poor claims history, significant dricing offences, etc) as they rarely offer any benefit, especially if you are low risk generally.

I'd say that other than the driver profile (age, claims and offense history), the location of your home makes the biggest difference. Oddly enough the vast majority of insurance firms never want to know the location of your normal place of work, which could be in a VERY high risk area compare to your home.

When I (mid 40s at the time) was looking for a replacement (brand/nearly new) car back in early 2017, I found that the difference for me between a new Mazda3 2L petrol SE-L Nav (not exactly a 'sporty car) and a nearly new (900 miles ex-demo) VW Scirocco 2L (180PS) GT (far more sporty) - both costing around the £17k mark (discount on the first via a broker and via Motorpoint on the latter) was only £25, i.e. around 10%. I was very surprised.

It just goes to show that being a careful driver (above 30 and under 75) and living in a low risk area can help enormously in keeping premiums low.