Have you tried to get a new quote from Admiral? It maybe that it's cheaper for new customers whilst renewals get a higher premium, standard lure tactics to get the punters in but whack the premium up the following year to make better margins.
Fortunately dual pricing by insurance companies is big in the news currently and some thing you can definitely take to a complaint if you find your new policy quotes more than your old one. Try using a different email address and name but keep reg and postcode the same.
Also don't forget not all insurers will be on aggregator sites because the aggregators have such high commissions so often the best deals are still to be had by doing your own research. It's just society has got a bit lazy and swallowed by the comparison site mass media. And don't buy for the sake of a free meerkat, again the campaign launched found this time last year and did really well initially but now customers are getting their renewals through and the premiums are getting pushed up to make up margins from low value entry level policies.
Rant over