I don’t have any doubt that the Hebrew in Genesis 1 when it speaks of days is describing a 24 hour earth day as we know it now. The bigger question is whether Genesis 1 is a literal historical record of how God made all things.
There are some surprising examples exist of brethren who absolutely did not accept evolution but were prepared to consider the 6 days of Creation in Genesis 1 as being other than literal. While the views of previous brethren don’t determine what is true, I am endeavouring to demonstrate a broader range of views was previously accommodated on this particular question.
EG Henry Sulley “As to the period occupied in the six days of the work of creation, we have no means of knowing how long a “day” is from the Divine point of view.”
Bro Walker stated similar thoughts a number of times, one example should suffice “we cannot agree to restrict the “days” of creation to literal days, and the original “rest” of God likewise to twenty-four hours! Critics will please be merciful to us” possibly a fair request!
Bro Watkins observed “sequence of events described in Genesis 1 is the same as the sequence that geologists have discovered by studying the rocks. This cannot be mere coincidence…” and went on to propose the days of Genesis 1 be understood as 6 days of fiats (or commands by God).
Bro Carter, as editor, commented at the top of Bro Watkins article quoted from above and said
“The Bible is a record of God’s creative activity in the beginning and onwards. It begins with creation. “In the beginning God created…” We cannot believe in the Bible and deny belief in creation. But when we ask how God created and seek to impose an interpretation upon the language of Genesis, we may make mistakes. Yet reverent enquiry can be pursued with profit if we recognize the limitations of our efforts. Different suggestions have been put forward at various times in the past, but we shall know finally the truth when Moses is again on the scene”
Alfred Norris was another who publicly stated acceptance of 6 days of revelation versus activity
“This is perfectly consistent with the view that the writer, Moses, is putting down what he heard, even describing what he saw, and announcing the end of each period of revelation as that day’s disclosure comes to its end. In other words, it seems to be very likely that God enacted the work of creation before the eyes of the seer, giving him the substance of His activity in six daily revelations”
Bro LG Sargent was criticised in the Logos Magazine for expressing (in the view of Bro HP Mansfield) insufficient certainty about Genesis 1. In in a strongly worded response to the pointed and personal criticisms of HP Mansfield, Bro Sargent refused to back down, stating instead he preferred to “leave the time involved in creation as an open question”.
Harry Whittaker concurs with Norris and stated “Six daily visions revealed to Moses or Adam or some primeval prophet” was seemingly “the most likely”” solution or understanding of Gen 1.” Bro Alan Fowler also expressed this view according to a review of his book in The Testimony Magazine.
A slightly different model was advocated by Bro Hayward who followed Bro Watkins in advocating 6 days of fiats originally being spoken by God and the work being done following this (with the use of parenthesis in the record recording the work being done at a later lengthier timeframe).
When the Watford arranging brethren notified the ecclesial world of their decision about disfellowshipping Bro Ralph Lovelock, they affirmed the unique creation of Adam (which I believe) and included the following “we do not claim to know in literal detail either the time taken or the methods used by God in creating Adam”. That was brethren Cooper (of CCA reknown), N Smart & H Tennant among others.
More recently in 2016, Bro Andrew Perry has expressed the view that the record of Genesis 1 reflects a “localised old earth” model. The account he thinks is a young creation in a specific location in the midst of a much older pre-existing creation. In this unique model Adam and Eve and specially created and later become the sole progenitors of humanity as those around were killed (despite the genetic and archaeological evidence to the contrary).
Obviously I have a different view to all of these brethren, however, their views demonstrate some things which are commonly insisted on today were not always held so dogmatically. However again our key focus should be on the Scripture, the key passages which relate to creation.
I understand some ecclesias may have added such a statement to their “Doctrines to be Rejected” relating to timeframes in Genesis 1. Requiring reading Gen1 as 6*24 hours of consecutive creative work as a precursor to fellowship would require significant rethinking on many previous brethren (who did not hold EC) who either held different views or were prepared to accommodate and publish them.
 Sulley The Christadelphian, 63(electronic ed.), 472. (1926)
 Walker The Christadelphian, 70(electronic ed.), 200. (1933)
 Watkins, P “The Days of Creation” The Christadelphian Volume 97 Page 6 (1960)
 Carter, J “The Days of Creation” Editors comment The Christadelphian Volume 97 Page 6 (1960)
 Norris, A. Where Science & Religion Meet” The Christadelphian Volume 102 Page 18 (1965)
 LG Sargent “What do we believe”, The Christadelphian Magazine Vol 103 page 460 (1966)
 Whittaker “Commentary on Genesis 1-4” Biblia (pp. 16–17) (1986)
 Nicholls, J “Creation & the Fossil Record” The Testimony Magazine Vol 67 Page 325 (1997)
 Hayward, A “ Creation and Evolution: The facts and fallacies” SPCK, (1987) see pages 170-177
 Clark, Cooper, Dean, Driver, Egerton, Johnson, Smart, Tennant, “Statement From the Watford Ecclesia”, The Christadelphian Vol 103 page 543-544 (1965),
 Perry, Andrew (2016) Special Creationism East Bolton, UK, Willow Publications page 45 see also pages 28, 43,