1. to be missing London while one is away
2. sypmtoms often associated with those of homesickness- but does not require one to have permanently resided in London
3. sometimes, but not always, a result of wanderlust
4. an incesant, inexplicable need to return to the the city on the Thames
5. pure. simple. sanity.
She sat alone, sipping her tea, feeling so Londonsick it was almost unbearable.