Having fired off a quick reply, I wasn't entirely correct. The Post Office is a separate business, but a member of the "Royal Mail Group", which also includes Parcelforce. Brian, I eat my words, with a side order of humble pie.

I quote:
Post Office Ltd is a separate company within and part of the Royal Mail Group that runs our 14,300 Post Office? branches across the country. We are the largest retail and financial services chain in the UK - bigger than all of the UK?s banks and building societies put together.

However, your council is now LBL (London Borough of Lewisham) rather than LBC (Lewisham Borough Council)!