The series is tentatively scheduled to run through July and August.
A decision on the tour is expected before the end of February.
Edinburgh, London, Cardiff and Dublin would host the test matches.
The Lions tour looks like becoming another victim of COVID-19.
The Crusaders coach has expressed his desire to help out his fellow Kiwi in 2021.
Scott Robertson said he's submitted a formal request to be part of the coaching lineup.
Officials have warned the tour could be pushed back 12 months.
The four 'Home Unions' make almost no profit from the five-week tour.
The two teams played out a drawn series in 2017.
Willie John McBride has called the proposal "nonsense"
The 'decider' would take place at Twickenham in June 2021.
The two marquee sporting events will run side-by-side.
Clayton McMillan will take over from Warren Gatland for the year, who will be on British & Irish Lions duties.
The All Blacks hooker will start in the biggest test of his career to date.
The Welshman planned to run away, until a phone call with a family member.
The former All Blacks hooker has only lost two of six tests at the helm.
The All Blacks haven't played England in a rugby test since 2014.
The former Wales captain has not played since leading the 2017 Lions to a drawn series against the All Blacks.
He derided the NZ coverage during the Lions Tour, but said he'd like to coach a Super Rugby franchise.
The former All Black has said he will never take the reins of the Lions again.