In the post was an illustration - titled 'Fight Them' - of an ISIS terrorist dressed like Jihadi John holding a sword in front of Big Ben, as a fireball engulfed the background with a tattered Union Flag flying in the wind.
Six weeks after this call to arms was posted via Telegram, terrorist Khalid Masood, who converted to Islam and was radicalised in prison, like many of them, launched his attack on the Houses of Parliament, in the shadow of Big Ben, killing four people and injuring many more.
(Despite the fact that Masood was implicated in a plot, as recently as 2010, involving a planned bomb attack on a Territorial Army base in Luton, and despite the fact that he had visited Saudi Arabia twice, "after carrying out a risk assessment and looking into his background, it was decided he did not pose a terror threat." - the police and the Home Office will be working frantically behind closed doors to cover their politically correct backs even as I write).
Telegram was also used by fanatics before the attacks on Nice in July 2016 and Berlin in December last year.
And the Metropolitan Police are saying that they may "never find out" the motive for this mass murder.
Are they stupid?
Apart from the background of Masood, who ticks just about every box as far as Jihadists go, can I offer the Metropolitan Police another clue as to his motive?
The website al-Islam proclaims that "Jihad (Holy Struggle) is an Obligatory Duty". They justify this by referring to their holy book “O Prophet! Strive hard agaunt the infidels and the hypocrites, and be firm against them, and their abode is hell, and evil is their resort.” Holy Qur'an (66:9)
Just to simplify this for their more simple readers, they go on to say that "Muslims should defend themselves if being attacked in order to preserve their faith, spread Islam, and stand against tyrants and oppressors. Allah made jihad obligatory, in all its forms, whether it is the jihad of society or self, speaking a word for the sake of preserving Islamic call Da'wah, or defending the sanctuaries of the Muslim nation. Jihad is considered among the best forms of worship with Allah, the Most High... The martyr who sacrifices himself and dies for the sake of his faith finds his place in Paradise."
Al-Islam describes itself as being the "official website of Ahmadiyya Muslim Community - an Islamic organization, international in its scope, with branches in over 200 countries".
This is quite an old group, founded in India in the 19th century. It teachings all assume that Islam is practiced in the context of a Caliphate. The stated aim of Islamic State is the creation of a new Caliphate.
I could go into far more detail, but should Scotland Yard's finest read this, they might find the clue they are looking for regarding a motive for Wednesday's attack.
Its really not that hard, Sherlock.