Archaeologists  have uncovered a ritual burial of 2,000-year-old human skulls - sparking the theory they could be the remains of Boudicca's rebels - as the London Crossrail excavations continue. The latest discovery of cremated human bones packed neatly into a cooking pot and set off at the side of the historic River Walbrook, in London, has experts questioning whether they were part of a gruesome ceremony. When about 20 skulls were found buried in clusters in the sediment of the historic tributary in 2013 it had been thought that they had got there down stream after being eroded out of a Roman cemetery to the north - but new evidence suggests otherwise. Scroll down for video . New find: Around seven human skulls (pictured) dating back nearly 2,000 years have so far been found as part of the latest discovery by archaeologists at the London Crossrail site near Liverpool Street station . Roman rummaging: One of the skulls (left) was uncovered next to a Roman road which has also been found. A piece of Roman figurative pottery (right) was also dug up during searches of the site . Digging for history: A cross-section of the Roman roadside ditch uncovered at Liverpool Street station . The estimated age of the human remains and the way they appear to have been disposed of has led to the suggestion that the bones could even be Boudicca's rebels. Scientific tests are continuing on the cremated remains, with the possibility the grim ritual theory may be confirmed and that most of the seven skulls found so far are heads of  executed criminals and rebels. A spokesman for London Crossrail confirmed the team was working up a number of theories. He said: 'We don't have any answers yet but we are looking into it.' The Boudiccan Revolt raged from 60-61AD and saw British tribes, under Boudicca of the Iceni, unsuccessfully try to defeat the Roman army. Boudicca was Queen of the Iceni people, a British tribe who lived in what is today Norfolk and parts of Suffolk and Cambridgeshire. The revolt resulted in Camulodunum, now Colchester, London, and Verulamium, now St Albans, being burnt to the ground while thousands of people on both sides lost their lives. A spoon from the Tudor period (left) was unearthed from a deep ditch, along with leather fragments (right) A spokesman for London Crossrail confirmed the team was working up a number of theories for the latest finds, which included cremated human bones packed neatly into a cooking pot . 'No answers': Archaeologists have uncovered a ritual burial of 2,000-year-old human skulls - sparking the theory they could be the remains of Boudicca's rebels. The bones are to be sent away for further analysis . A long needle believed to be from the Roman period was also dug up. It will now undergo scientific tests . Revolt: Boudicca was Queen of the Iceni people, a British tribe who tried to defeat the Roman army . The Boudiccan Revolt raged from 60-61AD and saw British tribes, under Boudicca of the Iceni, unsuccessfully try to defeat the Roman army. Boudicca was Queen of the Iceni people, a British tribe who lived in what is today Norfolk and parts of Suffolk and Cambridgeshire. Her name is an early for of the more commonly known name 'Victoria'. Her husband, Prasutagus, was ruler of the Iceni people, and the Romans allowed Prasutagus to continue as king, ruling on their behalf. But, when Prasutagus died, the Romans decided to rule the Iceni directly and they confiscated the property of the leading Iceni families. The Romans are also said to have stripped and whipped Boudicca, and raped her daughters. The revolt resulted in Camulodunum, now Colchester, London, and Verulamium, now St Albans, being burnt to the ground while thousands of people on both sides lost their lives. Colchester was the first target of the Boudiccan army and many of the townspeople were rounded up and sacrificed in nearby groves. The Crossrail team spokesman said a connection was not currently being made between the skulls from 2,000 years ago and Boudicca's rebels but the possibility has not been ruled out. Work to excavate 3,000 skeletons from Bedlam burial ground, at the site of the new Liverpool Street station that will serve the cross-London rail network, has now been completed. It took a team of 60 archaeologists four weeks, working six days a week, to remove the remains and record evidence for what may prove to be, in archaeological terms, London's most valuable 16th and 17th Century cemetery site. Among the skeletons discovered at the burial site - used from 1569 until at least 1738, including the Great Plague in 1665 - were a mother a her child buried side-by-side. They have now been transferred to the Museum of London Archaeology (MOLA). It took a team of 60 archaeologists four weeks, working six days a week, to remove the 3,000 skeletons previously found in the Bedlam burial ground, at the site of the new Liverpool Street station . Scientific tests are continuing on the cremated remains, with the possibility the grim ritual theory may be confirmed and that most of the seven skulls found so far are heads of executed criminals and rebels . Different theory: When 20 skulls were found in the River Walbrook it had been thought they got there down stream after being eroded out of a Roman cemetery to the north - but new evidence suggests otherwise . A close-up look of the Roman needle found as part of the archaeological digs . A decoration thought to be from the Tudor period was among the historic finds near Liverpool Street station . Crossrail workers are in the process of building a new ticket hall above the burial site - also known as Bethlehem and the New Churchyard - which was opened after graveyards around London started to overflow. It was used to bury London’s poor and religious non-conformists as well as patients from Bethlem Royal Hospital - the first dedicated psychiatric institution in Europe. Workers are now digging through medieval marsh deposits and Roman remains including a road that runs under the site. Archaeologists are expected to finish on site in September, after which construction will proceed on a new eastern ticket hall. Speaking last month, Jay Carver, Crossrail lead archaeologist, said: 'This excavation presents a unique opportunity to understand the lives and deaths of 16th and 17th century Londoners. One of the human skulls unearthed as part of the London Crossrail archaeology project . The Boudiccan Revolt raged from 60-61AD and resulted in Camulodunum, now Colchester, London, and Verulamium, now St Albans, being burnt to the ground while thousands of people on both sides lost their lives . New find: The Crossrail team said a connection was not currently being made between the skulls and Boudicca's rebels but the possibility has not been ruled out. The skeleton above was found at an earlier date . Careful work: The excavation of 3,000 skeletons (pictured) from Bedlam burial ground, at the site of the new Liverpool Street station that will serve the cross-London rail network, has now been completed . Crossrail workers are in the process of building a new ticket hall above the burial site - also known as Bethlehem and the New Churchyard - which was opened after graveyards around London started to overflow . 'The Bedlam burial ground spans a fascinating phase of London's history, including the transition from the Tudor-period city into cosmopolitan early-modern London. 'This is probably the first time a sample of this size from this time period has been available for archaeologists to study in London. 'Bedlam was used by a hugely diverse population from right across the social spectrum and from different areas of the city.' The Museum of London Archaeology is undertaking the archaeological excavations at Liverpool Street  on behalf of Crossrail. Scientific analysis of the remains will help provide new insights into the lives and deaths of early modern Londoners. So far, Crossrail has found more than 10,000 artefacts spanning many years of London's past across more than 40 construction sites. It is the UK's largest archaeology project. In 2013 and 2014, preliminary excavations at the Liverpool Street site in 2013 and 2014  uncovered more than 400 skeletons and numerous artefacts. The Crossrail project has already unearthed a number of exciting discoveries, including more than 10,000 artefacts at more than 40 construction sites. In 2013, workers made an 'unexpected and fascinating discovery' in tunnels underneath Liverpool Street Station, where the historic River Walbrook flows. The Crossrail team unearthed about 20 Roman skulls which were found buried in clusters in the sediment of the historic tributary. The Crossrail team unearthed Roman skulls in 2013, which had been buried in clusters at Bedlam . Working under the direction of archaeologists, the construction workers carefully removed the human skulls, as well as a collection of ancient Roman pottery. For safety reasons the archaeologists had to leave the work to the tunnellers as the skulls were buried as deep as six metres below ground. The discovery of the skulls and pottery was made below the site of the historic Bedlam burial ground. Bedlam hospital was a psychiatric asylum and patients who died while at the hospital were buried in a cemetery first established in the 16th century. Historically, Roman skulls have been found along the Thames tributary Walbrook during various excavations in the region. Prior to the discovery of the Roman skulls, workers also found about 4,000 skeletons buried in the Eldon Street area. These skeletons were found in August 2013 and were carefully removed during major archaeological excavations last year .
Seven human skulls, nearly 2,000 years old, have so far been uncovered . It is thought they were discarded as part of ritual burial on River Walbrook . Sparked the theory the skulls could be the remains of Boudicca's rebels . Excavation of 3,000 skeletons at new Liverpool Street site is now complete .