For the sake of conversation I offer some quotes.
time of the Buddha the Tantras were always taught secretly and selectively." - HH sakya trizin
"The Origin of Tantra
The tantras were spoken by the Enlightened Buddha himself in the form of his supreme manifestation as a monk. also as the great Vajradhara and in various manifestations of the central deity of specific mandalas. The Great Beings, Manjushri, Samantabhadra, Vajrapani and others, urged by the Buddha also taught some Tantras.
In terms of the four classes of Tantra, the Kriya Tantras were taught by the Buddha in the form of a monk, in the realm of the thirty-three gods on the summit of Mt. Meru, and in the human world where Manjushri and others were the chief hearers.
The Pung-Zang Tantras were taught in the realm of Vajrapani. Others were taught by the Teacher Buddha himself and with his blessings some were explained by Avalokiteshvara, Manjushri and Vajrapani while others were spoken by worldly gods.
The Carya Tantras were also taught by the Teacher Buddha in the form of his supreme manifestation in the celestial realms and in the realm called Base and Essence Adorned with Flowers.
The Yoga Tantras were taught by the Enlightened One when he arose in the form of the central deity of each mandala in such places as the summit of Mt. Meru and in the fifth celestial realm of desire.
The Anuttara Tantras were also taught by the Enlightened Buddha. In the land of Ögyan the Buddha, having manifested the mandala of Guhyasamaja, taught King Indrabodhi this Tantra. The Yamantaka Tantras were taught by the Teacher Buddha at the time of the subduing of the demonic forces and they were requested by either the consort of Yamantaka or by the consort of Kalacakra. The Hevajra Tantra was taught by Lord Buddha when he arose in the form of Hevajra in the land of Madgadha at the time of destroying the Four Maras. The Tantra was requested by Vajragarbha and by the consort of Hevajra. Having been requested by Vajra Yogini, the Enlightened Buddha, in the manifestation as Heruka on the summit of Mt. Meru, taught the Root Tantra of Heruka and, when requested by Vajrapani, taught the Explanatory Tantra. As for the Kalacakra Tantra. the Mighty Buddha went south to the glorious shrine of Dharnacotaka and there, manifesting the Mandala of the Dharmadhatu Speech surmounted by the Mandala of Kalacakra, taught this Tantra to King Chandrabhadra and others. Although he appeared in many different manifestations, actually the Tantras were taught by the Enlightened Teacher, Lord Buddha. " - Kyabje Trijang rinpoche http://www.abuddhistlibrary.com/Buddhis ... g%20Ri.htm
On guru rinpoche and shakyamuni "Guru Padmasambhava is a totally enlightened being. He is the supreme embodiment of all buddhas. On the highest level of the dharmakaya, Guru Padmasambhava is known as Samantabhadra or Vajradhara. The sambhogakaya Guru Padmasambhava is known as Vajrasattva, and in nirmanakaya form he is known as Buddha Shakyamuni or Guru Padmasambhava himself." - Khenchen palden sherab from heap of precious jewels
". In the Western concept of morality, sexual energies are usually regarded as a hindrance to the spiritual path. Does the tantra mean the acceptance of these energies and can they really help us along the path?
A. If they are rightly used; if used by the right person, at the right time and correctly, they can be a very great help. The story is often told of King Indrabhuti, who told Shakyamuni Buddha that he would rather be reborn as a wolf in the jungle than undertake a spiritual path which demanded the renunciation of worldly things. The Buddha gave him a special teaching, the Guhyasamaja teaching, of which we still have the transmission. Mere external renunciation is, of course, of little use; one can renounce something externally and still be very attached to it! True renunciation is the renunciation of attachment. In any case, King Indrabhuti was of the very highest type of person and he and his entire court actually attained enlightenment while the Buddha was giving them the teaching!
However, most tantric practitioners are monks who are not allowed worldly pleasures and who must, of course, be celibate. King Indrabhuti attained enlightenment immediately, but we only have to read the story of Milarepa to see the difficulties that even gifted individuals undergo." - hh the sakya trizin http://www.hhthesakyatrizin.org/teach_interview4.html
So from what I can infer it seems that most traditional masters maintain that, Shakyamuni buddha taught the tantric methods, it seems the traditional view is that he taught mostly mahayana, but also did teach some tantra, for example if he manifested in a certain manner and than taught.
As far as the mention of one vajra word being heard accordingly.. Can it be said then that people of vajrayana position did hear vajrayana teachings ?