Old haulage companies

Thinking of old companies, during 1955 whilst trunking along the A1 between London and Sheffield, an incident happened that has puzzled me to this day. A Rigby Wire trunker pick up a lady of the night and left her in his cab whilst he went for tea in Kates Cabin. When he came out he found that she had defacated on his bonnet and wiped her rear end on his delivery notes. I wonder if he got a clear signature. Bill.