Every year I go from one car insurance company to another, last year direct line, this year Churchill.
So I get my auto renewal form through from Churchill for £442, so I call direct line and get a quote for £348.
I then call Churchill who sent the auto renew for £442 and they can drop to £359, so I saved £83

Why did they not send that quote out first..................naughty!
But they are all the same, so if your insurance is due make a couple of calls.

This happens to me every year too. We do a quick search online, then call up our existing provider, tell them we are leaving if they don't come close and surprise surprise they always manage it. We even did it with the AA this year, told them it was about price and not service (they have the most vans on the road). They knocked £100 off and upgraded the policy.
It is staggering but definitely worth a phone call. Stick to your guns, you are leaving unless they get close.

Yes I call the AA every year as well and get another good discount.............but how many just accept the price quoted?

Too many Graham.
I had another classic today. I rang the insurers to notify them of a change in vehicle later this week. He mentioned that our quote for next year would be coming soon and it would be x amount. He asked if I wanted to go ahead with that. I to,d him I would have to check the comparison sites first. He then discounted the price without question by £70,knowing I was still going to check.
I then checked and whilst there were others cheaper, they were not like for like (higher excess, etc)
I still rang back and said that the quote was £20+ off the nearest other insurer. He told me hat the discount applied was the most he could do. He hen put me on hold when I said I would have to think about it. A few seconds later he came back with personal injury cover (normally £29) for both my wife and I at no cost. I said I would ask my wife. I then said could that price be knocked off instead and no cover applied. Without batting an eyelid, he applied the extra cover and knocked £20 off.
Thank you very much, I will now accept that.
So, All in they discounted my original quote by £90 and threw in cover worth £29.

I always tell them to stick it when they try to lower a renewal quote, I make sure I tell them they shouldn't have tried to overcharge me in the first place.

All of the companies do it. If you can negotiate lower and stick with them, the loyalty card also comes into play next time (Ah yes,  I see you have been with us since..l we don't want to lose your custom...) if they get close enough I stay with them, working on the principal that next year I will face the same issue regardless of who I end up with.

I called my insurance do get rid of some of the optional extras that were on my policy to save a bit of money. After a chat, I kept the extras, but the overall cost of the policy was reduced!