She had no knowledge of this case or the complainants and could not opine as to the truthfulness of their allegations.
Beckham, who has pleaded not guilty to three charges of indecently assaulting girls aged under 12, says the alleged offending simply never happened.
The charges arose in 2019 after two women each told police Beckham had indecently touched them several years earlier.
One of the complainants alleged two incidents in which Beckham touched her genitals. The second claimed he reached under her top and touched her breasts.
Under cross-examination by counsel Martin Hislop, each of the women insisted the offending happened regardless of other children and adults being nearby.
They each kept it secret, not fully realising it was wrong until they were adults.
They denied any collusion, saying they had only shared their experiences briefly.
The second complainant said she only became aware of some aspects of the other woman's complaint at trial.
She could not remember much about her childhood but this offence was "burned into her brain like an ugly brand", the second complainant said.
In her evidence, Dr Ahmad said it was a common misconception that children who were sexually abused would immediately report it to someone they trusted.
But there was no typical reporting pattern for child sex abuse. Many children did not report the offending at all or delayed reporting it.
Just as an immediate report could be true or untrue, so could a delayed one. Timing did not affect credibility.
Abused children did not necessarily disclose offending even when asked about it by an adult or a peer. There could be many reasons for this, such as fear of an offender, respect for family or fear of not being believed.
Many children showed no physical or behavioural symptoms of sexual abuse.
In a small number of studies where there was corroborating evidence, such as where the offender had made videotapes or the child had contracted a sexual disease (neither of which was suggested in this case), victims showed a significant tendency to deny or minimise the severity of their experiences. Only half of those victims reported the experiences during forensic interviews.
A New Zealand study showed a significant number of children had not been to a doctor for suspected sexual abuse and had no behavioural changes prior to a diagnosis of gonorrhoea, which was made unexpectedly after a routine swab. Again, when interviewed, children in that group had similarly low rates of reporting.
There were a multitude of reasons why children and young people delayed reporting or did not report abuse: feelings of having no one trusted to talk to or listen; a lack of language skills; fear of not being believed or taken seriously; feelings that nothing will change; a sense of embarrassment; a reluctance to burden others; a fear of getting themselves or someone else in trouble; a fear of a loss of control of the information that was shared; not wanting to upset parents or wanting to protect parents; and threats from the offender.
Some researchers described a "pressure cooker" effect children go through of wanting to tell but also withholding it until the buildup of that effect increases - often in adolescence - and they finally disclose.
Children often knew the offender and in these cases, especially where the offender was an authority figure, reporting rates were often lower and delays longer.
Victims of familial abuse were less likely to report it in childhood or adolescence due to obvious power differentials and dependency needs.
Children with less supportive parents were more likely to delay than those with supportive parents.
Offenders used methods to normalise sexual abuse, could take advantage of children's natural sexual curiosity, and desensitised children to physical abuse.
These things could confuse a child, who might not then realise what had happened to them.
Children may also enjoy some aspects of the abuse, which could induce feelings of guilt or a belief they had been somehow complicit, creating a further barrier to reporting.
Abused children did not necessarily avoid their abuser, often continuing to have contact with that person due to other benefits of the relationship or because they had no choice, Ahmad said.
Under cross-examination, she confirmed false complaints were possible and that people looking back on past events could be mistaken in their perceptions of their alleged offender's actions.