I recently picked this brass plate up with some other items I purchased & thanks to Tom B. who has researched it , can confirm it's from a packing crate used by the lawn mower manufacturer Fellows & Bate . Grenade collectors are probably familiar with their FB marked No36's . They also made mortar bombs , aerial bomb parts & a host of other ordnance related items . An interesting slice of our history from the early days of WW2 that , I hope , members will find of interest .