This subject is being debated around this time of the year, every year. See this thread:
http://www.nappyvalleynet.com/mums/view ... +catchment
This is a very contentious subject - and I'm not sure if, in the case of Honeywell school specifically, the council can do much about it. Rather the school itself (through its board of governors) will have to agree new admission procedures to address not only the issue of short-term renters, but also the shortage of school places available once all the siblings are counted.
Other than increasing the number of school classes (say from 3 to 4, not sure how feasible that would be), I would suggest a "siblings catchment area" to about say, 1/2 mile (or whatever distance agreed and based on previous records) and give sibling priority first in that radius, then, non-sibling applicants to be admitted on distance living in that radius, then out-of-catchment siblings, etc. So, basically those who rented short-term, got in and then moved further away will no longer be prioritised over the local children.