There is always a risk of some sort of attack, but i think London show during Olympics that it's well prepared to meet that threat ahead of, perfect confidence here as services go, a good *.

I have been here spectator before, people and security around is all is very good.

I had conversation with my wife last night and she want me, she said we used to do it and i suggest our reservation whether she and the young children will come and watch.

It is one of the world's foremost marathons, from the very start here in southeast Landon, the security challenges will be considerable, more than 36,000 are expected through the start line, they are beginning to a red temperary infrastructure to cope, not just with the many runners, but their support teams and tons of equipment. This Sunday will be Adam S first marathon, security wasn't really a factor he considered before the event in Boston, he says he will certainly be more aware now.

It's scary what happened, i fall along with hearts, i didn't debate where i want to still take part, for me i want to help out the people life, i will do my best, thinking about Boston is well known, it's a terrible event.

Pounding the 26 miles through London, there are of course the world's famous landmarks where many thousands will gather to watch, protecting those spectators is a difficult challenge, but London is well used to coping with huge events and tightened security.

The events in Boston were absolutely horrific, obviously our thoughts with the victims and their families, but in London the police will be taking every possible precaution to make sure that the funeral tomorrow and the marathon at the weekend can go ahead.

The ultimate destination for the runners the finish line near Buckingham palace and like Boston, an area where many friends and families will gather to cheer them warm, but it's another vulnerable spot.

We want people to enjoy the great charm with the city of London doing what it does the best, but with that comes all the inherent problems and risks of having a lone wolf, the idiots, the feral faction and indeed the criminals and the terrorists, so it's a big big job to manage.

The organizers who show their determination to press on with Sunday's marathon, there is no specific threat and certainly it seems the vast majority of runners intend to keep come and carry on.

Mark K, Sky News.