We sat in the pleasant surroundings of the Jack Straw's Castle inn near the flagstaff on the northern perimeter of the Heath. Warm beer was a welcome antidote to the cold.

"I cannot understand, Holmes, how the fact that there were two species of hadrosauriwhatsit can possibly be significant."

"Quite simple, I imagine. The first species, whose calls sound like those of a trombonist executing the final bars of Thaxted, are our megalosaurus's preferred prey. The second species, meanwhile, whose call is more violinlike, are a related animal which moves with the herds of the first. But our carnivore will not attack this second species."

"It will not?"

"I will stake my life on it. These animals are not prey. Their flesh is shunned by our megalosaurus, which will nevertheless follow them in much the same way a lion will follow an animal it is incapable of bringing down, such as a rhinoceros, in the hope of finding other herbivores it can bring down. Nevertheless, Watson, whoever is controlling this creature is playing fiddle with the Devil. And he is about to walk through that door, right about - now."

The doors opened to admit a shabby-looking street musician, similar in appearance to the poor devil I had examined only a day earlier.

"Mr. Green, I believe", said Holmes. "Formerly music teacher to the family of Professor Challenger of Enmore Park. No, don't trouble yourself to pull out that revolver. You will find that almost every person in this hostelry right now is an armed member of Her Majesty's Metropolitan Police."

Eerily, as if Holmes were some macabre puppeteer, every single one of the establishment's customers turned round and raised their hats to the newcomer.

"You will perhaps be mystified as to how I know your name. You are, of course, an adherent of the Fenian cause and a proponent of Home Rule for Ireland. The merits or demerits of that question I leave to politicians. I involve myself only at the point when people believe their political causes justify murder. Your principal mistake was in presenting yourself, in disguise, to your former employer as a meat wholesaler of the name of Glass. 'Glas', as Watson doubtless does not know but I certainly do, is the Gaelic for Green, a childish conceit which led to your downfall. You noticed several months ago whilst tutoring Professor Challenger's children that the notes of the trombone appeared to induce a blind killing rage in the juvenile megalosaurus chained up at the other end of the drawing room. The notes of the violin, meanwhile, served only to attract its attention and cause it to follow the violinist round the room. It was after learning these facts that you formulated your plan.

You planned to remove the beast from confinement using two of your Fenian confederates, and train it to attack human beings. The small number of bites inflicted on his serving staff had convinced Challenger that the creature did not seek out human beings as prey; it needed to be taught to do so. And you, Mr. Green, have been teaching it to kill for the last twelve months. And why have you been doing so? Why, in only one week's time, His Majesty King George is due to attend an open air concert at the Parliament Hill bandstand on the Heath, where the final piece on the programme will be Mr. Spring-Rice's inspired lyrics to Thaxted by Gustav Holst. In fact, it is only the final note of that tune that sets off the beast, am I right?" Holmes began whistling the final few bars of Thaxted.

The musician�s face palled.

"For pity�s sake," he exclaimed, in a pronounced Dublin brogue, "you do not know what you�re doing. "If you value your life, if you value all our lives, stop!"

And Holmes did stop, drawing out that long penultimate note, and laughed. "Indeed", he chuckled. "How could it be otherwise? We have Professor Challenger's word that you practised Holst's Jupiter in the beast's presence without ill effect. Jupiter, of course, would have been safe to practise, for in Jupiter, which is otherwise identical to Thaxted, the final note never resolves. Were you, perhaps, hoping that the beast would wreak such havoc among the crowd that His Majesty would be trampled?"

The scarlet-haired Fenian shook his head. "You do me an injustice, sir. If you had only troubled to look further into the cast of the orchestra, you would have discovered I was to play the principal trombone. I intended to place myself directly before the monarch of your despicable island, blowing my horn for all I was worth. The beast would surely have taken the ermine-laden buffoon after it had finished with me."

Holmes nodded. "I see you are a man of courage, if a misguided one. I am offering you an honourable way out."

He extended a hand, proferring the trombone. The Irishman nodded sadly and accepted it. Holmes picked up the untouched pint of ale he had been nursing since we arrived, and held it up as well.

"A last drink for a condemned man."

Green accepted the pint, and drained it with gusto. Then, he turned round to the assembled police officers and cried:

"Fianna Fail!"

- before striding out through the inn doors into the white murk. We saw no more of him; but heard, droning in from without, the clear, calm notes of that timeless patriotic hymn which, I became more acutely aware than ever before, apply to any country, any King, and more especially to that great country we all hope to become citizens of upon our end.

Then, suddenly, there was a great thundering crash, and a hideous roaring, and the notes of the trombone ceased as the instrument itself was flung out of the fog, bent double, towards the window where we sat.

"Gods, what a beast! It will take a troop of soldiers with an artillery piece to kill it!"

"I think not", said Holmes. "That pint of ale contained enough strychnine to kill ten elephants. Now, I believe there is time for me to consume another less dangerous pint before we repair to the bandstand, where I believe the local brass ensemble is currently setting up to practise. I fancy I could stand to hear that tune again."

And he clicked his fingers for the barman to bring him another beer.