A tree surgeon paralysed after falling 50 feet from an ancient horse chestnut is suing the National Trust.

Jamie Yates, of Carleton Road, Chichester, was injured while working on Trust land at Morden Hall Park in south west London in December 2009.

Christopher Wilson-Smith QC, told Mr Justice Nicol at the High Court that Mr Yates, 26, had no memory of the "catastrophic" accident which has left him in a wheelchair.

He was using a chainsaw on the decayed and infected 80 feet high tree which was nearing the end of its life and it was probable that a branch he was using as an anchor point for his safety rope snapped.

Mr Wilson-Smith said that Mr Yates, who was self-employed and working for an independent contractor, had never dismantled a tree of such height before and did not have the certificate that would have qualified him to carry out sectional felling.

The court must establish whether the Trust was liable to instruct contractors, none of whom had appropriate certification.

National Trust denies negligence or breach of duty.