The only thing that puzzles me is why they were approaching you in the first place. On one hand, I do understand that agencies have to deal with a lot of flakey escorts (sometimes just unreliable people, but sometimes because of the amount of newbies who go with agencies - I was less reliable back in the days when I didn't know what I was doing!) so perhaps these guys are looking for reputable indies for that reason. But if they have a successful setup in another city, they should be inundated with applications and have their pick of fresh new faces to take advantage of.

Maybe that's just the case with the more well-known London agencies/parlours, though? Either way, I would be questioning the motives of any agency who were scouting for girls, especially if they were promising the moon. But if you keep up your indie work and always check in with your own security buddy, then you shouldn't be at any more risk than just working indie. No one here can predict what you will or won't earn, of course.

a certain type of women

My cynical instinct is to suggest that they are looking for a certain type of gullible victim upon which to enact a scam most foul. *Dickensian fog swirl*

I guess if you wanted more work, they were willing to pay you your current rate, you carried on doing your indie work and you carry on doing your usual checks then hey why not? Free advertising really isn't it?

i have been approached to work for an agency with all the usual low fees, photos, driver if i want bla bla bla anyway was  a bit surprised that an agency would approach me, not me them as is the usual way. Anyway have read a lot about agencies and the pros and cons on this site so well aware about them. The agency has an established agency in another city and have set  up in my town. Should i give it a whirl part time?. I am not a naive women so well aware on what i should look out for.   

You surely should be surprised that an agency would approach you, sounds too good to be true lol. Hope this agency is different from all the others which I doubt very much. Goodluck!