I'm not clear why its worth your time either. Now that is funny! Thats not difficult he only needs to Google LBA and he will get loads of templates.

No....HMRC might take that view (I've not checked so can't confirm), that does not mean the the independent courts have the same view. Could be irrelevant if not directly linked to the case.

Yes guilty I’m a Rover enthusiast. Why a lesser amount to your proposed settlement? The courts would look unfavourably on you with this course of action. Why into his bank account? In my view you would be better sending him a cheque for the amount your proposing with the condition if he presents the cheque he is accepting that amount in Full and Final Settlement. From what you say this is a B2B issue. The courts won't intervene to the value of work done. Sorry for you but ericsbrother and Consumer Dude are correct on this one.

I see that there are three issues here, admittedly connected, but need to be treated separately. First potentially criminal behaviour , the OP claims that he/she was threatened by this locksmith. This an issue surrounding Criminal Law, as such is not a Civil issue. Report the alleged instance to the police and let them sort it out. Secondly the issue of “I am now negotiating a further discount on the basis that, if I make a complaint to the Police about Reading locksmith's threats it could hurt their business.” My view is that this is unethical and potentially criminal behaviour on the part of the OP, and he/she should cease this course of action immediately. Irrespective of the alleged action of the locksmith, to try and extort money or services through the use of threats is in breach of Section 21 of the Theft Act 1968. Finally the OP refusal to pay for worked carried out by this locksmith. As the OP, by his/her own admission did not have a quote prior to commencement of work I see that there he/she has little choice but to the pay the invoiced amount in full. If payment is not made a can see that the OP would be taken to court, which would likely increase the overall liability as costs would most likely be incurred.