Interpretation of subcontracted out R&D expenditure

Please could someone clarify a question on subcontracted R&D expenditure. This area is covered in the HMRC manual here http://www.hmrc.gov.uk/manuals/cirdmanual/CIRD84250.htm

If a company carrying out R&D has a sole trader make up mock-ups or models, would you treat this as subcontracted R&D or the external supply of materials and services? Would the answer be different if the sole trader modified the models slightly from the orginal plans, using their expertise to improve the practical outcome from the design?

The particular question relates to an SME claim and whether or not this expense should be subject to the 65% restriction.

We would have thought this wasn't subcontracted R&D but a contract to provide services. However experts in R&D claims have questioned this interpretation.

We'd be interested to hear other opinions on how this should be treated.

Thanks.