Lpg Insurance?

So I've done a search on the threads and they are all a few years old so i thought it might be worth asking now.
My last two cars have been factory fitted LPG (a Ford & a Vauxhall ) so I didn’t thinking insurance would be a problem.....but I just got told my insurance company would not touch the discovery because the lpg is classed as a modification (of course it is I just didn’t count this in my budget or think it would be a problem).
My question is who are you insured with and how do you go about getting an install certificate if one didn't come with the discovery??
I’ve had an eye watering quote!
Any ideas please, Its a Discovery 2 53 plate?
Thanks for reading

Worth getting LPG serviced and certified. But first ensure your petrol side is up to scratch as that effects the running of the LPG. Insurers can be problematic when a modification involved. I had my 110 v8 3.5 LPG on open system via the SU CARBS it ran like a dream. At the time Swinton were okay until they hiked up the cost fro 500 to 1000 beerchits. Then I contacted Adrian Flux which made a major difference. But due to family caring issues I had to sell Pending where you live Postcodes crime figures count as much a farming areas that have high theft rate. It worth having the petrol side serviced first then later finding a LPG autogas Booklet from main garages which list petrol and servicing.

Never had an issue with lpg just start getting quotes

I'm insured with Tesco on the Freelander, and when I had the Range Rover too. Both LPG, no problems with insurance on either. Listed as LPG engine modification on the certificate. I think it only put the policy up by about £10, and when I've needed to make a claim it's never been a problem.