I've just moved into a new house and have been cleaning out the drain in front of the garage. It should have a cover, but it's missing. Hence the need to clean it out. I've tried to get hold of one the right size, but they all seem to 148mm square. The hole is slightly smaller, approximately 140mm. I presume it must be an imperial size, as the house is from the 1970's. Where can I get one from?
Thanks
Dave