Can contracts be signed without solicitor having loan pack?

Formal loan offer was issued last Saturday. I have a copy that was e-mailed to me. It's a full formal loan offer - not an approval in principle. Solicitor's loan pack was supposed to be issued at the same time but hasn't arrived in the solicitor's office yet.

Pressure is immense to sign contracts this week. Solicitor is refusing to allow contracts to be signed until hard-copy loan offer and loan pack arrives.

I understand why a solicitor won't allow contracts to be signed until they are satisfied that a formal loan offer had been issued. But as the solicitor has received the soft copy of the formal loan offer as proof, is there any reason why she won't permit signing of contracts until the hard copy arrives?

Of course there is a reason. To protect you. No loan offer is real until you have paper originals. This used to be covered by having a loan clause in contracts. You can never be too careful and sounds like your solicitor is doing a great job.

How about you tackling the pressure, who is putting this pressure on?