CHAPTER Twenty-Six THE NIGHT CHASE AND THE MUDLARK.
'I'LL board her to start with,' said Hazell, whispering to Racksole.
'I'll make out that I suspect they've got dutiable goods on board, and that will give me a chance to have a good look at her.' Dressed in his official overcoat and peaked cap, he stepped, rather jauntily as Racksole thought, on to the low deck of the launch.

'Anyone aboard ?' Racksole heard him cry out, and a woman's voice answered.

'I'm a Customs examining officer, and I want to search the launch,' Hazell shouted, and then disappeared down into the little saloon amidships, and Racksole heard no more.

It seemed to the millionaire that Hazell had been gone hours, but at length he returned.
'Can't find anything,' he said, as he jumped into the boat, and then privately to Racksole: 'There's a woman on board.

Looks as if she might coincide with your description of Miss Spencer.