If you signed a lease and have since moved leaving behind the leased vehicle, for whatever reason, you are in default of your agreement by not paying or working out an arrangement prior to leaving. You need to find out, as camoscato said, what your responsibilities are in the contract you signed. If the employment transfer was beyond your control, you may be able to prove this to the lease company by supplying a letter from your employer -- or you may need to supply proof that you are no longer in the UK (proof of address). This may or may not convince them to work with you.
Otherwise, all you can do is notify them on the location of the car, but you are still bound by contract to fulfill your lease agreement. If you cannot do this, as they said, you would have to pay an early termination fee. Either way, it's going to cost you money in the end and negatively affect your credit as well (if the lease company doesn't come to a mutual agreement).
Also wondering, out of curiosity, if 'visas & citizenship' is the best forum to answer this question?
