Retraining teachers across to Computing can be done; I understand it happened in Scotland a couple of decades ago, and New Zealand did something along those lines not too long ago (Bell, Andreae & Robins, 2008). Teaching the BGE should certainly be possible for such people, and given the opportunity to do further learning (day-release, Open University?) teaching up to Nat 5 and beyond should be possible too.
As a beginning Computing teacher, of fairly mature years, it does worry me how few new Computing colleagues I will have. Without the teachers, how can a school offer Computing? Though the Universities do try, certainly the PGDE route into Computing teaching is not attracting enough applicants to fill the places which are funded and available.
Another thought is to find a way of bringing people in from industry, though giving up a well-paid job to do a full-time PGDE is a big ask of someone considering a career change. Is it feasible to perhaps do the University training component of a PGDE part-time, in the evenings or at weekends, and only require full-time commitment once the school placements start? There may be people out there ready to make the jump to teaching, but the financial chasm of a PGDE year followed by a Probation year is perhaps too wide.
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