Lord Lichfield, the Queen's cousin, has been criticised by a senior member of staff for taking up too much space at his ancestral stately home.

A leaked internal memo at Shugborough Hall, near Stafford, complained that other similar venues have more areas open to the public because "they don't have Lordy nicking half the rooms!"

The remark - from Education, Interpretation and Collections Officer Lizzie Nurse - relates to Lord Lichfield having about half of the 17th-century building as his private residence.

Shugborough Hall belonged to the family of photographer Lord Patrick Lichfield, the fifth Earl of Lichfield, for generations, but is now owned by the National Trust, which leases the 900-acre site to Staffordshire County Council.

In the memo, Miss Nurse described a recent visit to Erddig country house near Wrexham, Powys. She claimed there were far more rooms available for visitors to view.

The memo reads: "I don't know if you have read my thoughts on Erddig which I visited a couple of weeks ago.

"I was impressed by their house and their servants' quarters, both of which seemed fuller than ours (mainly because they don't have Lordy nicking half the rooms!)"

It was sent out in response to negative feedback on how job duties at Shugborough have changed this year. Costumed guides now have to adopt a 'first person' technique, playing the role of 17th-century workers. Some staff believe the scheme is not working.

Miss Nurse gave advice in the letter on dealing with difficult customers who challenge the role-players.

She wrote: "Shugborough is now marketing itself as a fully first person experience, and will continue to in the future.

"Even if all the management were blown up tomorrow, it would only be a matter of time before the new management realised that this is the best way forward.

"I appreciate that you have not had any organised training before you started this new technique, and I can only be thoroughly impressed by how well you've all coped.

"If you let me know the usual dodgy questions we can work out a suitable response and then share it with the rest of the staff."

She adds: "There will inevitably still be some cocky fools, but if you ever get anyone like that who doesn't get the hint, then just ignore them!"

Estate manager Richard Kemp said the letter was the sort of memo which would be sent around any business in response to operational problems.

He said: "It was a private internal letter to staff and not intended for public reading. What Lizzie was trying to say is that although we may not have as many rooms in the mansion house open to the public as other places, there is still so much to do here.

"Unfortunately the way she has chosen to word it has come across in a negative way.

"Visitors who regularly take traditional National Trust tours around stately homes sometimes ask us 'is that it?' because they are only allowed to look around half the building. But what they don't realise, until it's too late, is that there is not just Shugborough Hall to visit but a huge servants' quarters, a working farm and masses of parkland as well."

He said visitor numbers were up 14 per cent from last year, and that staff had a good relationship with Lord Lichfield.