In Chapter 43 of The Hallmarked Man, Strike texts Robin that Barclay had been on surveillance of Jim Todd in the afternoon and that Todd had made a “pointless” Tube journey. He’d sat on the Circle Line for an hour, going round, then got off where he got on.
In Chapter 44, Pat tells Strike that Dev Shah had been on Jim Todd and that he’d been on the Circle Line again.

In Chapter 46, Strike tells Robin: “Midge says Jim Todd’s made two more calls from telephone boxes and has been riding round the Circle Line without going anywhere again.”
Strike texts Robin, “There’s definitely something fishy about Todd. Cant’ find him in any records. Think he’s using a fake name.”
In Chapter 54, Robin follows Todd to Liverpool Street station and then onto the Circle Line.
Todd remains on the Circle line for nearly an hour playing a game on his phone and glancing around at the surrounding passengers. Once or twice he shifts seats. Robin makes small changes as a precaution – even though she doesn’t think he’s spotted her – putting on a pair of clear-lens glasses, taking off her beanie hat and turning it the other way out so that the red fleece shows rather than the black. She also changes position, sometimes sitting, sometimes standing.
Robin keeps feeling little ripples of anxiety about Strike and Bijou Watkins.
“Aldgate… Tower Hill… Monument…”

“Strike had form on hiding things about his sex life, as Robin knew only too well…“
“Gloucester Road… High Street Kensington… Notting Hill Gate…”
Robin continues to think about Strike and Bijou and Bijou’s pregnancy.
“Baker Street… Great Portland Street… Euston Square…”
The train doors open and a gaggle of teenage girls enter the compartment, clutching their high street purchases, chatting and laughing. Two of the girls are barelegged, “their flesh mottled beneath the miniskirts not even an icy January day would scare them out of wearing.“
“Farringdon…“
An elderly woman rises from her seat right besides the teenage girls. With surprising speed for such a rotund man, Todd takes the vacated seat. “Now he was positioned right in front of the mottled, miniskirted legs, his small feet crossed, his head bent over his phone, seemingly intent on his game.“
“Barbican…”

Robin watches Todd as he stealthily extends his phone underneath the skirt of the miniskirted girl standing with her legs apart for balance. Robin makes an involuntary movement. Todd looks straight around at her.
‘OI!” A tall black man wearing headphones points. “I SAW THAT, YOU FUCKING NONCE!“
Jim Todd plunges out into the crowd at Barbican station and disappears. Robin leaves to look for him on the platform but he is nowhere to be seen.