If you have a solicitor in London and an attorney in the US, you should have the advice you need. Asking on a bulletin board is not likely to get you better advice.
It is not clear if you are bringing a suit in the UK or in the US ? What are you suing for ? Is it a small claims action ? Is it for personal injury ?
Before filing a lawsuit you ( or a lawyer) will normally consider three things:
1) Is there a "cause of action" against the would be defendant ?
2) Is there a Statute of limitation bar ?
3) what is the probability of proving the action and actually collecting from the defendant ?
You should also bear in mind that in the US, every state has its own laws. For example in the case of statute of limitations you may have only one year to file before your case is time barred. In some cases you may have as little as 60 days.This might vary depending on the type of action.
Depending on the sums involved and the likelyhood of success, litigation is likely to be a very time consuming and emotionally draining experience. In many cases even successful litigants regret the wasted time and money actually expended in pursuing an action. Unfortunetaly it tends to be an emotional experience for the claimant (plaintiff) in this type of action. For the defendant it is usually a matter handed to their liability insurers who have no emotional attachment whatsoever. They also have a lot of experience in handling such cases, and are very often notorious at protracting and delaying cases to the point that the claimant is simply worn down or gives up.
Of course if every claimant considered this seriously, there would be far fewer cases brought, and you should not necessarily be dissuaded by these comments. Nevertheless this is often the reality and no matter how angry you are, you should consider the realistic timescale and likely chance of recovery before embarking on such a venture.
A lawyer who is familiar with this type of litigation should be able to give you a realistic picture, and you should listen carefully to what they have to say. a lot of potential litigants are driven by their own view of justice and recompense, rather than what is the reality of the situation.
Good luck.