In a few moments Tom understood. Their new colleague, Della, was on secondment from the Cabinet Office Security Detail and was obviously on a fast track to high office. In the last five years, since leaving Cambridge with a first in Politics and Economics, she had been on four secondments. This was her first post in an operational department though, her previous positions had only been in data analysis and although her security clearance was in theory higher than Harry's she did not have the field skills to match. Harry thought it better to limit her briefing to what she needed to know rather than the full details of this case. Hence the need for a separate briefing for Tom.
So far their stakeout had only produced limited leads. The tramp that Tom had spotted was one of the most suspicious. There seemed to be no sightings of him except on the way to and from the park. Local police had not spotted him sleeping rough and had not had occasion to move him on for begging. Even in London most of the down and outs were known by sight, even if they were not known by name. Della had walked past the tramp on her way into the park and her only comment was that he was not as smelly as other homeless people she had encountered. She had not reported any other suspicious activity near the park shelter.
Tom spoke briefly to Della on his way out of the office and arranged to meet her for a drink after that park closed so that they could compare notes. She seemed concerned that things seemed to be moving slowly. Tom realised that she would have to get used to the tempo of operations in MI5, it was either like watching paint dry or so fast that you did not have time to think.
The first thing Tom noticed as he walked through the park through lightly falling snow was a set of almost obscured foot prints leading to and from the shelter. As casually as he could he took a close look at the prints as they left the main path and took a quick photo with his phone. He looked at the picture more carefully as he sat down in the café and sipped a hot chocolate. Jerry who he was relieving waited a few minutes before getting up from his table and Tom texted him with the picture after he left the building. Jerry replied quickly, he had not seen anyone near the shelter but had come in by another entrance so had not passed the path on his way to the café so the prints may have been there before he arrived. This was strange, perhaps Della had missed something, she seemed to be quite bright and watching was a simple task. Tom texted Harry and asked that the night-shift team enter the park and search the shelter under cover of darkness. If a drop off had been made they might be able to find out its contents.
As the park shut for the night Tom walked to the pub where Della had agreed to meet him. She was almost half an hour later than planned and apologised and blamed the delays on the bus. Tom glanced out of the window. The snow was falling more heavily now and the traffic had slowed to a crawl. Tom and Della traded small talk until they were sure that they were not going to be overheard as the pub filled up and the noise level increased. When Tom raised the question as to whether Della might have missed something in the park she became very defensive. She was sure that no one could have approached the shelter without her noticing, unless it was while she had to visit the toilet. Tom groaned inwardly, first lesson of stakeouts, empty bladder before and don't drink too much. That could explain it, they had missed the drop off. If the night team could recover it they might stand a chance of getting a lead on the pick-up man though.
Tom saw Della to the bus stop and waited with her until one going her way arrived. She apologised again for her faux-pas and promised to learn at least that lesson. As he walked back to his flat he felt a vibration from his pocket. Harry, and not a text but a call, that was very much not the norm.
Tom listened as Harry quickly told him of developments, using hints and code phrases rather than anything that could be easily understood. The night team had recovered and copied the contents of the dead letter drop. It had been disguised as a geocache, though not one listed on any of the official sites. The secrets being passed had been hidden as a microfilm dot in the cache log. Harry paused, what was being passed was information on their own department! Where was Della?
Della seemed surprised when the armed team burst into her flat. She had been so sure that her cover was still secure. Tom's habit of collecting the phone numbers of young ladies he met while working had paid off this time. The cashier from the café had been most helpful after a meal and a few drinks. This time of year so many people wanted to use the toilets in the café rather than the cold public ones in the park that the café owners had started to lock them and only hand out the key to paying customers. Tom had joked that he bet they had many lady customers making use of them today, but the cashier said that it had been a quiet day, only one young lady had asked for the key when she came back in from the cold after taking a walk to the shelter.