Leylandii stumps won't grow back. In fact most conifers won't regrow from brown wood. The only problem you may get is from fungus as the stumps rot. If possible get someone in to 'stump-grind' them out.

We have taken Leylandii out on three places in our present garden and always left the stumps behind and planted shrubs between them. They just go away after a while. They were not huge. If they are huuuge, as in the garden we used to have, it would cost a fortune to get shot of them. Depends what you are planning to do after removal of these pernicious trees.

I've used a gardener who specialises in stump grinding and in my opinion it was money very well spent.
Shop around, i got 3 different quotes which i thought was useful.

you can drill into the stumps and get some stuff that will let them rot without getting fungi on them i do believe . bamboo knows the stuffs name .

Thank you all for your thoughts.

Volunteer - I have never heard of stump and grind. Having never felled any before. I shall look into it. Thanks

Dmj - We had 1 enormous one to fell, with at least 8 massive branches about average 15ins /20ins approx. We haven't got as far down as the stump yet, but it is massive.
It had to be felled as cracks were appearing in our house. And the surveyor said this and the few others were the problem.
The others we can cope with, but this huge one will need attention I fear. Many thanks.

Louse1 - Yes I shall look into stump grinding, and get a few quotes. Thanks

noseypotter - What problems do fungi cause. Hear I show my complete ignorance, but this is how we learn.
I shall contact Bamboo, and see what this magical mixture might be. Many thanks

the fungi can find its way into healthy plants if you just leave the stumps . it doesnt matter if your having the stumps ground out so much but you will normaly have some sort of remnance left even with a stump grinder . i would cut them down low and leave them for that reasen myself . a stump grinder is basicly a heavy duty drum with big metal teeth that is dropped over the stump and it chews it right up and out of site into big flakes of wood . the large tree needs dropping from top to bottom probably bye a professional tree surgeon to be quite honest .

Just found this - you know what to do now, but Noseypotter is referring to honey fungus - unfortunately, any stump killing chemical treatment (as I told you to use already) does not prevent possible honey fungus growth later on. Any source of dead, dying or rotten wood in a garden is the perfect home for honey fungus - but most of the time, it doesn't happen. Honey fungus, once established, will also destroy live, healthy plants as it spreads, depending on which particular strain it is. Other forms of fungus which may appear do not have the same impact.

Hello Bamboo & Noseypotter.
I have to admit, that I didn't realise that fungus could kill all plants etc, if left.
I shall keep an eye out on the other 4 stumps.
Since we moved in, we have completly cut down many things, as the garden was so overgrown. And are pleased that many of the bushes are starting to grow back again.
Would the fungus attack the bushes too?
Mind you hopefully we won't have any fungus! but our garden is at the bottom of a hill, so can be quite damp. we have lots of moss.

Kind regards
wombat

ps Thank you for your help.

As I said, its not fungus generally that you need to concern yourself with - any old stump may develop toadstools or bracket fungus as part of the process of breaking down. But honey fungus (honey coloured toadstools in September) is the one

We have a very persistent coppiced hazel stool that was left after 2 tree trashing parties we held. Food and drink and H&S precautions observed. It occasionally produces fungii from the stool in autumn. We once took down a very large pear at another gathering we had, while clearing our previous garden of the most amazing trash. A bunch of old rover scouters who cleared various scout sites of old trees, assisted, plus the neighbours of that garden. We payed for the trunk to be clean cut to the ground and the root ground out, as we wanted a summer house in that spot. I hasten to say we have planted a lot of trees too.

I can finish my previous answer now - my keyboard packed up halfway through the last one!
Honey fungus is the one to worry about,the rest are not an issue.

Hello Dmj
What a great idea of a party, to fell the trees and tidy up.
I wish we had thought of that, could have had a house/Garden warming party, and they could all took a bit err a lot of wood back home with them.

Bamboo
I shall keep an eye out for Honey fungus. Thanks again.

Kind regards to everyone for all their help and advice.