Chopped down some conifers that had TPO's

When you say 'chopped them down' do you mean all the way down to the ground or to the height of 2 metres or under? Even trees with TPO's need to be maintained.
You should go to the Council and ask their advice because to have a TPO on an evergreen hedge completely flies in the face of s8 Anti Social Behaviour Act 2003 which is the statutory objectives surrounding the leylandii disasters. It states that members of the public can contact the local authority about getting evergreen hedges cut down to a height no more than 2 metres on any property which has had a complaint lodged against it. The Council also have the authority to get an order to insist the hedge is maintained to this height by the owner of the property. So, I would say that you have had to maintain the hedge (providing you haven't cut it down to ground level!) take the letter form the tree surgeon along with you and also state that the above legislation completely contradicts the TPO. You will probably scare them with the amount of paperwork they will need to do and they will remove the TPO!

The tree's have been chopped to ground level. Where can i get a copy of the S8 act ?

The internet

http://www.opsi.gov.uk/acts/acts2003/ukpga_20030038_en_9#pt8

This should take you directly to Part 8 High hedges, print it off and read it carefully to make sure you sound confident and well informed.
Your defence would be the letter from your tree surgeon as he has said the hedge was dangerous, damaged, etc. Did you find out the hedge had a TPO before or after you chopped it down?

I knew about the TPO from the previous owners, they got the impression from the council that they did not have a problem with removing the tree's but they would not go above the Historic poeple.

They also got the feeling from the council that if they were chopped down they would not be to bothered. I know it sounds the complete wrong way to go about it and normally I would agree but it has worked so far.

I know there is a planning rule where buy if a building has stood standing for more than 5 years without a planning warrant then it no longer requires planning, I chopped these 3 years ago and thought there might be a similar rule

I would hope that a Judge would consider the views of a tree surgeon, timescale, S8 act and that new growth means the original purpose of my tree's is no longer required.

As the trees are no longer there the TPO is irrelevant, however you may be fined for b reaching it. But in your defence you haver the letter from the tree surgeon and the Law to back you up. It is always the case with issues like this that one thing will contradict the other. Even the Anti Social Behaviour Act Part 8 is contradicted because if the Council come an chop down a hedge to the Statutory requirement of 2m, then it flies in the face of not chopping a hedge down by more than a third to prevent damage and death to the plant which is another Law. Councils are less and less enthusiastic to carry out the instructions under the ASBA 2003 P8 for fear of being sued!