Case argument required for civil claim

BackGround

In 2006 i purchased a olex watch from a privat person. Before the purchase i attended a well known high street official rolex dealer to have the watch verified as original and to put a value on it.
I was accompnied by a friend and the seller. Having requested that the watch specialist in the shop confirm the rolex to be genuine I asked hime to vaue the watch. The valuer dissapeared into the back and some 15 mins later returned to confirm the watch to be genuine and the value to be £35,000. The value was confirmed on a sighted valuation for insurance purposes form.

In 2010 i dropped the watch off a local rolex dealer for service who informed me that he watch was not genuine. This was confirmed by Rolex in writing to the dealer.

I tried to locate the seller but it becale clear that this was a scam i had beed duped into. I wrote to th high street shop and had no reply.
I then instigated county court proceedings against the high street chain and submiited the claim to my local court. My claim was for negligence and for £35,000 - being the value of the watch.

The defendant responded defending the claim suggesting that the watch valuer was not quailified to value and only looked in a catalogue to get the value of a similar rolex watch.
The defendant further requested the case be moved to a local court.
The local judge\'s instructions were that we choose a joint expert to value the watch and then to have 4 weeks to see if we can come to a settlement.

The expert provided a report which confirmed that whilst the movement was genuine, the diamonds and strap were non rolex...in fact rolex have never made such a design iether in 2006 or currently.
The watch was sold to a person in the middle east and someone prior to 2006 modfied the watch.
The expert also placed a value of around £3,000 - £4,000 as to the current value..in an auction for this grey market watch.

It is clear that the valuation is totally incorrect and that the defendnat could not have iether looked in a catalogue - if he had he would have known no such model was in circulation - or called Rolex - because they would have told him the same.
I have had an offer to settle th claim of £3,500 from the degendant whcih i rejected and suggested I would acept £15,000 if they settled before xmas.
Waiting for repsonse from them.

I am looking for a good argument - in writing that i need to submit to the court in preperation of the trial. I want to claim £35,000 as though i was claiming from an insurnace company.
BTW i paid £16,500 for watch, the defendants are aware of this

I was made redundant some time ago so please when submitting a price be aware of this. I would hope to award this in the few days
Rgds
OR