Excerpt from the BMA website (on the page that SVH linked to below):
"Best interests
In the past, circumcision of boys has been considered to be either medically or socially beneficial or, at least, neutral. The general perception has been that no significant harm was caused to the child and therefore with appropriate consent it could be carried out.
The medical benefits previously claimed, however, have not been convincingly proven, and it is now widely accepted, including by the BMA, that this surgical procedure has medical and psychological risks. It is essential that doctors perform male circumcision only where this is demonstrably in the best interests of the child. The responsibility to demonstrate that non-therapeutic circumcision is in a particular child?s best interests falls to his parents.
It is important that doctors consider the child?s social and cultural circumstances. Where a child is living in a culture in which circumcision is required for all males, the increased acceptance into a family or society that circumcision can confer is considered to be a strong social or cultural benefit. Exclusion may cause harm by, for example, complicating the individual?s search for identity and sense of belonging. Clearly, assessment of such intangible risks and benefits is complex. On a more practical level, some people also argue that it is necessary to consider the effects of a decision not to circumcise. If there is a risk that a child will be circumcised in unhygienic or otherwise unsafe conditions, doctors may consider it better that they carry out the procedure, or refer to another practitioner, rather than allow the child to be put at risk.
On the other hand, very similar arguments are also used to try and justify very harmful cultural procedures, such as female genital mutilation or ritual scarification. Furthermore, the harm of denying a person the opportunity to choose not to be circumcised must also be taken into account, together with the damage that can be done to the individual?s relationship with his parents and the medical profession if he feels harmed by the procedure."
It seems to me that what this is saying is that the only demonstrable benefits that the BMA can see are those to do with cultural identity and fitting in. It is interesting that they also mention FGM.