NOSTALGIA

i have finished the game and am now completing the quests im stuck on the jewel of siberia quest after the monster flew away from london where did it go hav searched high and low no sign please help

The quest where you have to chase the monster is another quest, not "Jewel of Siberia". That quest was actually initiated when you first went to Australia and spoke with Jack who aspired to be a sky pirate. He later told you that the monster traveled north, where you will get a prompt that the monster headed towards London. It doesn't mater what altitude you search for it actually. The game doesn't prompt you directly over London; you'll have to search around the vicinity of London and eventually you will get a message that the monster headed northwest. If you are really curious about it's next location, search near where Greenland is. Regarding the "jewel of Siberia" quest you have to search north of Saint Petersburg in the gap between 2 mountains.

IVE ALREADY DONE THE JACK QUEST AND KILLED THAT DRAGON I SEARCHED SIBERIA THEN IT SAID THE MONSTER HAD GONE WEST NEAR LONDON THEN IT SAID IT HAD GONE NORTH NORTHEAST WHICH I PRESUME IS NORTH AMERICA LOOKED ALL ROUND IN HIGH ALTITUDE AS IT SAID TO CLIMB AND CANT FIND IT

Please kill your caps lock. I would assume you haven't exhausted google?

yes no walkthroughs guides or sites can help

Have you tried GameFaqs?

If you would've read carefully the dragon is near Greenland.
As for the "Jewel of Siberia" quest go here:
http://www.gamefaqs.com/boards/genmessage.php?board=950323&topic=52364373

yes i did finish the jack quest coz when i went back to tell him id killed the dragon he decided to be an adventurer and i never said the monster was a dragon plus i no its the jewel of siberia quest coz it says so at the adventure agency and in my notebook and jacks was a random enconter not a quest from the agency all i want to no is where monster went after it goes west to london i found it twice once in siberia then near london cant b much clearer no wot quest im on and yes tried gamefaqs

Sorry about that last post, I edited it. When I was on the "Jewel of Siberia" quest, it never told me to head over to London. I just searched north of Saint Petersburg in the gap between the two mountains. This should trigger a cut-scene and a battle.
Edit: Face northeast of Saint Petersburg, travel in that direction (should fly over the lake), and you should see a dead end between 2 mountain ranges. When you fly toward the deadend, it should trigger a cut-scene.