explicit messages saying he was ` looking forward to putting you over my knee ' , it is claimed .
the married father-of-four has not returned to the costello school in basingstoke , hampshire , since the correspondence came to light last month .
` although i have been very grateful for the many messages of support and understanding , i have to put both the interests of my family and the school community first .
` it is therefore , with huge regret and disappointment that i have taken the very difficult decision to resign headteacher of the costello school .