It may just be wishful thinking on the part of holders that we get an offer, but the normal premium tops at the moment is about 40%. However this is for "normal" established trading companies and not one such as OXB with such blue sky potential as well as current earnings building up from product licensing.
If we say start at 38p then that is only a 53 bid on conventional takeover maths. I have though always thought (and posted) that any tentative initial offer would be not less than the high 60s and for a take-out bid would be £1.30+, so The Bull you wanting northwards of £1 really is not entirely fanciful in the event of either a contested or a straight take-out bid. Even so at that price OXB is a mere plankton in the sea for such as Genentech!